If you plan is to build a turbo engine, then I would select a custom engine builder that specializes in LS turbo engines. Billy Briggs at Motor City Speed. Billy used to work at W2W with Kurt, but owns his shop now.
http://www.motorcityspeedonline.com
Kurt Urban might be out of your price range, but you might contact him as well.
Your cost for the engine is depending on the components that you chose, so your budget cost is depending on the quality of the parts that use in your engine. Quality parts meaning US made parts, not the overseas parts.
Jeff