Getting your design to match your budget by experimentation can be a little tricky, but with a little math there's really not much to it. The volume of an object is proportional to the cube of its size, so you can calculate the new size as follows:
Yes, well, there are days that I don't feel like computing this either, so we've created this nifty little calculator tool. Just enter the price that we're now quoting, enter the price that you'd like to pay and bam! There's the scale you need to apply to your object to get it at just the right size for the price.
Do you need to make your object match your budget? Use the Size Calculator to find the right size!