Absolutely do NOT put used shoes on ANY child, ever. Shoes form to fit a foot, and are not designed to be worn by two children (or two adults). The only shoes I've ever saved to "hand down" to another child were dressy shoes that were only worn a few times.
However, you don't have to buy shoes for a baby for 50 dollars, either...you realized he's going to outgrow them in a few weeks! :) They go through shoes pretty quickly at this age, although my youngest, who is 15 months old, has been in the same shoes for about 3 months (yay!) but ready to outgrow.
My suggestions would be to stay away from anything vinyl, plastic, etc, as shoes made from these materials are not good for feet. Leather is best, but you can find nice leather shoes for much cheaper than what stride rite charges, just be prepared to size them yourself or have "inadequate" help. I know everyone is so thrilled with stride rite (my mom swears by it, all my shoes came from it) but I, personally, am not super plussed by their shoes.
Once my oldest was walking well, we put her in what's basically known as a "skater" tennis shoe...wide, cushy sole, well padded ankles and heels. You can get nice leather ones, and they are very attractive, and can be thrown in the washing machine (yay!). I think in the early years we paid around 30-40 a pair, depending (brands include Etnies, DC, Adidas, AirWalk, K Swiss) and they've gotten a little more expensive now that she's in children's sizes (she wears a 1.) I don't know what shoes stores are available in your area, but try a Foot Locker (or something like that)...that's what always worked best for me.
My youngest, all summer, as been wearing a pair of Adidas sandals that are essential made out of foam. They have a heel strap and two top straps that velcro, so they are completely adjustable to fit her foot well and they are super comfy. She loves them. (However, she's walking/running, etc, and is 15 months old. She's been wearing them since 12 months.)