[Perfectlap]

I will never understand the point of negotiating a purchase price on a car while at the same time trading your car in. You are only giving back the savings you obtained in the negotiation by underselling your current car.

My suggestion is to sell your 993 on your own, there is growing demmand for these cars and the engines have a good reputation so the high mileage wouldn't scare away an enthusiast and those are the guys willing to pay above private seller blue book.
And in terms of buying, you have an enourmous amount of leverage as a Boxster buyer. There are tons of good examples. The Carrera GT paint and extra trim options are nice but the special edition isn't significantly more valuable than a regualar 2004 BoxsterS. Its added value comes from its options not because its limited in production. This applies to some very low mileage Porsches but not this one. Don't overpay for the 550 edition.

p.s.
post a picture of your 911 if you can. I see a growing number of guys restoring these cars and flipping them for a nice profit! No one wants to do the work or spend the money. Kinda like a house I guess..