I just found 3 pairs of reasonably priced, normal sized accurate Prada boots on ebay after literally 5 minutes of looking. There is absolutely no need to short change the costume by getting inaccurate soled boots.
This is NOT a budget costume if you're looking for something 501st approved. If you just want to cosplay at your local convention and be a bright purple bounty hunter, nobody will stop you. But since it still seems very easy to find the right boots, I see no need to lower the standards.