Fortunately for you used body kits for your model can be had for $500-1500 all day in Japan. Unfortunately shipping alone will be at least 1k out of japan. There are not a ton of people into body kits on this forum so I suggest searching on
http://vipstylecars.com/main/ as they have numerous "vip" style Q45s of your model and you may locate one within your price range. The closer you are to California the better your chances of finding a kit in the US. I know K-break makes a nice kit for the FGY33
BTW a "budget" build may not be as suitable as you think. A Q45 or any 15-20 year old luxury car requires a strict "budget" on maintenance alone. But if you insist on doing a VIP build you may want to widen your budget for some emergency funding.