What do I do when i want to keep my coins but want something I have dreamed of as far back as I can remember?

I have come across an opportunity to purchase a 1969 Ford Mustang Convertible, and I am torn between my collection and this car. I have done a little research on this car and have found that it is potentialy a very valuable automobile, but I will have to part with some of my coins to finance it. When i came upon the car the seller wanted $10,000.00 for it, after viewing it and researching it, I made an offer of $5000.00. It does need a little work, the right front quarter panel has a nice ding in it(needs new quarter panel), the hood has a small ding in the front but can be repaired with a little effort. there is absolutely no rust on this beautiful car, the interior needs a little restoration, nothing to major, but would benefit from a carpet replacement, new seat skins and some good old elbow grease to clean up the rest, also the kick panels in the front and the rear side panels are missing, but these parts are readily available through some aftermarket reproduction parts houses at a reasonable price. It's gonna need a paint job, new wheels and tires, the typical cpr(Calipers, brakes and rotors), rear drums, shoes and hardware. Some suspension upgrades would be nice but not required. Well the seller counteroffered with $6000.00, i then countered with $5500.00 and he accepted. so i figure with about another $3000.00 i will have me a very nice Pony!! But now to the coins, i have about $1300.00 on hand and my brother is going to loan me the rest to buy it, but I have to have him paid back in one week, so in order to do this I will have to sell a few of my babies. Not sure which ones to sell but there are a few i refuse to part with for example my 2009 early releases ms70 UHR $20 double eagle. and my $5 and $10 2008 pf70uc buffalos. the rest is up for the chopping block. But exactly wich ones? I'm not sure. I have also considered selling my 1999 honda shadow 750 ace?! I am so lost at this moment!! I am going to complete the deal at 2pm tomorrow.

Well, wish me luck and pray for me to make the right decisions. And God bless you and the best of luck with your collections and future aquisitions.