Tundra,
I have had the same dilemma- first it was for the tri logo Jawa I bought last year. I decided to sell off a big chunk of Kenner ROTJ and ESB cards to fund it (about 30-40 MOCs). I wasn't 100% sure, but I decided, hey, you can pick up ESB and Jedi cards every day of the week on ebay/ forums. I took the plunge and did it, I haven't regretted the choice I made for a second. It dramatically reduced the quantity of my collection, but massively improved the quality. It is sat on a shelf on my stairs and every time I walk down the stairs I genuinely smile at it :lol:
I have just sold off another batch of my collection- MOCs, POTF and a VC Jawa to fund another "grail". Time will tell if I regret it. The only ones I already miss are my POTF figures. In all likelihood I will pick these up again and have the thrill of the chase to once again complete my loose collection.
If anything selling items off does help you decide what you truly value in your collection.
So, for example, if a GDE logo'd Jawa came up for sale tomorrow, would I sell off the rest of my loose run and some more MOCs? Hell yes.
It really is a personal choice, only you can make it. A word of warning, Soren is bang on the money- once you start picking up high end items it does make the "ordinary" seem exactly that. Ordinary.
Good luck and I will cross my fingers for you :wink: