Hi J.,
I think you'll be fine if you did your own pseudo program at home, if $ is an issue. I didn't do a "program" per-say, but I did make sure to teach her many things before it came time for pre-school. When pre-school time came, she was too advanced for it, and wasn't accepted (it was a small "free" program for kids who really need it), and now in kinder, she is actually ahead of most of her kinder peers. She is doing 1st grade stuff, and is already able to read at a slow pace.
We also had $ issues with regard to day care or pre-school, so we decided on teaching at home. Surprisingly, the main things I did, and still do, is constantly correct her on her pronunciation, her sentence structure, and expanding her vocabulary. As soon as she says something incorrectly, I stop her and let her know the correct way. Colors and shapes I incorporate into her foods on how I cut them and how I place them on her plate, so it's fun. Of course, coloring is important to get colors down, so there's coloring every day, even now. Numbers and alphabet started with just memorizing the ABC song, and learning 5 new numbers every week. Once she could count and recite all of her alphabet, I began showing her the letters and numbers.
It's all just been pretty great. The leap frog learning books are the best. I credit them with teaching her the basics, before I got to her. She played on those books for hours. I have a 2 yr old and a 13 month old at home too, and I do enjoy the time I have when I only have 2 for a few hours, so I do know what you mean when you say it's appealing to have 2 morning a week with only 1. For my family, my sanity had to be put second, while we decided that our monetary situation needed to come first, since we didn't want to have to budget in order to have necessities (diapers, milk, warm clothing, etc.)
Everyone's reasoning on yes or no to preschool is different. You already provide your child with the main benefits of preschool: socializing, group activities, music, etc.; all you really need to do is add some basic teaching. Get a leapfrog, and start with the basic books. Buy one at a time until she has the one book down and then move on.
I think you and your daughter will be fine.
Good luck!
Mari