Looking into an adaptive bike for Brextin's 3rd birthday

We have two trikes that allow us to push him - but they are not intended for special needs children so I need to figure out a way to adapt them. I am looking into pedal adaptive that would allow us to Velcro his feet to - so when we push him - his legs would actually spin - but at this website http://www.flaghouse.com/Adapted-Tricycle-Accessory-Foot-Pedal-Attachments-item-5875 they want $78 - are you NUTS!! Why is it that everything that is needed for our children costs so much money. I am seeking out my relatives to see if anyone can be creative - and make them for us cheaper -

Another website that looked promising is http://www.amtrykestore.org/ They might even donate a bike to your special needs child if a therapist/doctor refers you and there is a financial need. They offer different accessories that might be helpful to adapt one of his bikes to fit his needs.

I also went to amazon.com and found these bikes as a possibility:
http://www.amazon.com/gp/product/B002OHD2PC/ref=s9_simh_gw_p200_t1?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=center-3&pf_rd_r=1RXFPZG6K00MG5SZ8D62&pf_rd_t=101&pf_rd_p=470938811&pf_rd_i=507846 (I really like this one)

http://www.amazon.com/gp/product/B002MOXRTI/ref=s9_simh_gw_p200_t2?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=center-3&pf_rd_r=1RXFPZG6K00MG5SZ8D62&pf_rd_t=101&pf_rd_p=470938811&pf_rd_i=507846

http://www.amazon.com/gp/product/B002ZZ1T0S/ref=s9_simh_gw_p200_t3?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=center-3&pf_rd_r=1RXFPZG6K00MG5SZ8D62&pf_rd_t=101&pf_rd_p=470938811&pf_rd_i=507846

http://www.amazon.com/gp/product/B001E6OUZK/ref=s9_simh_gw_p21_t1?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=center-4&pf_rd_r=1RXFPZG6K00MG5SZ8D62&pf_rd_t=101&pf_rd_p=470939031&pf_rd_i=507846

http://www.amazon.com/Little-Tikes-615221-Smart-Trike/dp/B001UE85DO/ref=sr_1_1?ie=UTF8&s=toys-and-games&qid=1267372545&sr=8-1 (I really like this one)

I allows find it tough to find gifts for our special little guy - but I think this would make a wonderful third birthday gift - so when we go on walks he won't have to be in a stroller or his wheelchair. Can anyone else recommend any other suggestions?