I would get this Chicco balance bike!
http://www.amazon.com/Chicco-Bullet-Balance-Training-Bike/dp/B004SN4YHK/ref=wl_it_dp_o_pdT1_nS_nC?ie=UTF8&colid=ZGACSDNH45T9&coliid=I26M2Z1YYZDWI6
Of course you'd have to buy a helmet too, and that would put you over $50. Most of the ones I've seen on Amazon are $15-30.
ETA: I'd also consider buy this! It is awesome!!
http://www.amazon.com/Melissa-Doug-4071-Shopping-Cart/dp/B000VO3GPG/ref=wl_it_dp_o_pdT1_nS_nC?ie=UTF8&colid=16SBMNUYGI6LJ&coliid=I36QOS7N80DRF4