RIght heres what i think you shuld do. Buy the ice because by the sounds of it its a great deal, then also if you have the cash buy like a £70 da bomb or something along them lines off ebay. Then what you should do is practise stuff that your not so confident you can do on th ice on the other bike, then when you have a few crashes it wont matter. When your more confident with a move try and transfer off the cheap bike onto the ice this way you will be able to strectch your skills on that particular obstical with out scraching and denting your frame.
Oh and P.S dont listen tothe haters, there ust jealouse the cant get that kind of deal.
Ashes.