A Bike for Nicholas

We recently entered Nicholas into a bike giveaway contest where he received over 500 votes and had 28 bikes entered into the contest but sad to say he didn't win the customizable rifton bike. I fell in love with this bike and easily visioned Nicholas riding one, however the price tag is definitely out of our budget. So it was suggested by several that we turn to this site for help. Ballpark price for these bikes range anywhere between $1400.00 to $2000.00. Nicholas would require several modification to the bike such as a back rest with harness, different handle bars, and an attachemeht that would allow myself or his nurse to steer; all of which are additional charges to the cost of the bike. Any help you could provide will be greatly appreciated.