IMO 3600 is too much for an 06. I'd say that 06 isn't worth more than like 2800 TOPS, even if it's in excellent condition with a clean title and all. If I were in your position, I would wait for a better deal on a used bike. You can probably get a 2010 used with super low miles for 3500. In 2010 Yamaha fixed the cylinder base gasket oil leak issue (very common with the TW). So I'd go for that over an older model. But you can still get a used 2010 or 2011. I'd say it's worth waiting a couple months for if you don't see one right now.
Oh and welcome to the forum!