Suggestions on Planning a BUDGET Disneyland Trip.

Costco has discount ticket packages. You might want to look into those.
There is a Target a few blocks down the road from the parks. I highly recommend going there to pick up snacks, easy breakfasts, flats of water etc and keep those in the hotel room so you aren't paying park prices for all of your essentials. Staying off grounds is cheaper than on site. We only do day trips so I can't recommend any particular hotels in the area personally. If you do want to stay on site Paradise Pier is the cheapest of the 3. AAA offers some good packages if you are a member.
Bring your own rain ponchos from home if you plan to have them for the wet rides like Splash Mountain or Grizzly River Run over at California Adventure. They are insanely expensive in the park.
Make sure you go to Town Hall in Disneyland to get your daughter a "Happy Birthday" pin. They are free and it's a lot of fun to wear them all day and have cast members and guests a like wish you a happy birthday. My boys make a point of wishing everyone they see wearing a button a happy birthday because they love it so much and knows how special it makes them feel for their birthdays.
There are lots of good restaurants just outside of Disney, some of which you can walk to by simply walking across the street.
One thing about the end of September. Their Halloween Time starts and the hours get a little wonky at Disneyland some of the days when they have their Trick or Treat Party. The Trick or Treating costs extra and the park closes to all other guests. California Adventure does stay open later on those nights. Take a look at the park hours for the time frame you are interested in going to make sure everything you want is running and what times it's running. I do have to say, if you can afford it, the Trick or Treat party is a ton of fun and worth it. We really enjoyed it a lot and are going again this year. Also, the first weekend of October is Unofficial Gay Days and the parks can be pretty busy. As I don't know what part of the end of September you are talking about or if you'll be running into October I don't know if any of this effects you but I wanted to bring it up just in case.
I love Disneyland, my home away from home :)

We went in August. I would recommend first of all downloading ride max and preparing well for the trip, by studying up on what rides you want to go on, shows to see and so forth. Then you will get the most for your dollar.

I investigated tickets sold on Craig's list. They were considerably cheaper but I didn't want the hassle or the risk. But maybe it would have been a fine option. Have a friend of a friend who bought tickets that way and it was fine.

We stayed at a good neighbor hotel and got a package through costco, for 2 park hopping days for 4 of us (baby didn't count). We just went one day to DL and another to Calif Adventure, whereas most people seem to go 3 to 4 days. But I think a good visit to the 2 parks is do-able in two days if you go PREPARED (educated). Also, Doing so definitely took some investment of time for us, but it was worth it. Also, I liked some of the benefits of a Costco package...which you can read about on their travel website...one benefit being the character dining.

Bring your own food in. My cousin and her family brought a cooler in each day with PBJ sandwiches, grapes, etc. I have heard some people get sent to store their food in lockers when bringing in A LOT of outside food; but that if you make it less conspicous there's not a problem. My cousin actually had a little cooler. They looked through it to check for glass was all.

Good luck! We still spent more than I hoped...but definitely less than the average!

There are stores that sell souveniers cheaper including Kmart and Walmart. They even have coupons in the coupon books.

Were going next month with 6.5 people and made sure there's a mini fridge/microwave in our room. Were having breakfast in the room and will pack sandwiches for lunch. Were also close enough to walk back and forth so we don't have to pay for parking.

Here in FL. My family and friends get a rental house, that way they can purchase food and cook things at the house. They also buy meal plans at the park. Sometimes they offer FL Resident packages and I can get them with proof of my drivers license. I ask for every discount, AAA, FL Res, group, etc. ASK, it never hurts and they might find a great deal for you. Buy cheap toys/shirts etc, at a a store outside the park. Don't forget your camera! Have fun!

use priceline or another similar site for a hotel, staying off site & using a site like this can save you a ton & stay at a hotel that has a breakfast, many have hot breakfasts that are pretty good now & you can eat before you leave

you said disneyland so i'm not sure if there is more than one park there? like in disneyworld but you dont need parkhopper tickets. just go to one park each day, especially with kids you just spend all day getting from one to another.

you can take in water/bottled drinks & soft sided coolers, take in snacks at least & sammies if you want, we choose to eat breakfast at the hotel, take snacks, & then leave in the late afternoon for a meal off site, & then return for the evening, then we will snack some more & possibly grab a pizza or something on the way back to the hotel.

for souvenirs I would set a limit, you can find t-shirts, small toys etc before you go then give them while you are there, you will save a ton & then possibly just let your child pick one thing from the shops while there, mine dont even know the difference & sometimes love the stuff i get them more than what they pick there