About half of all transactions that closed in our metro market last year were new construction.  My client base is no different, I've represented buyers with just about every reputable builder (and if you don't know who in your market is reputable, that's precisely why you DO need representation in new construction).  And without exception, they offer $x in closing costs or upgrades or discounts IF and ONLY IF you utilize their in-house lender partner.

The question you have to ask yourself is: "Where is the breakeven point?"  Because, my friends, NOTHING in life is free.  That incentive that you are being offered is built into the price or the interest rate or the junk fees from the lender.  You have to make an educated guess about how long you're going to be in that home and figure out when you have recovered that 'incentive.'  If your interest rate is 1/8 higher with the builder, but you get $10,000 in assorted incentives, but you're only going to be in the house for 3 years, then yes, you would use the builder's lender.  But if you think it's the Forever House and you will pay off that 30 year fixed note, you are better off with the lower rate.

Also, ask for a good faith estimate.  Builder's lenders need to provide them just like any other lender who is competing for your business.  Often, they choose not to do so, preferring to quote over the phone.  Get it in writing so you can make a fair comparison.  And run it by your buyer's agent-we are professionals and we see different scenarios every day and can provide some pros and cons to your options.

Long story short?  Don't assume that you HAVE to use the builder's lender.  And don't forget to shop it.