Restricted "Bigger" Bike!

[NeoReloaded]

Hey guys ive been searching for a nice second hand Aprilia rs 125 but with only £1500 cash i have no chance in hell! So until i do my full test later this year i was thinking of getting a bigger bike but having it restricted to 33 brake which i suppose would also help me get use to bigger bikes aswell?! What do you guys think on this kind of subject and also how much is it to get the bike restricted?

p.s im 18 and on a CBT.

Thanks