I think the following things....
I think that's a bit pricey without seeing it first. My first reaction if Mellvis came home and wanted to buy another SR for 1500 would be to say no since we already have one, but if it was in IMMACULATE shape, then I'd say go for it. Oh, and if it were in red since I'm not a huge fan of the purple. What a bike is worth to you might not be the same as what a bike is worth to someone else. It all really depends on your desire to buy the bike and his desire to sell it.
What is the VIN? Does it have the red or purple paint? Was it manufactured in 78 or 79? What shape is the chrome in? Are there any pics for us to see? Is the seat foam, leather, and pan in good shape? Are there any indications of it being laid down, either on the tank, sidecovers, or side of the clutch or points covers? Is there any literature, manuals, service records, etc to go with the bike? Does the little tool kit come with it? Does the VIN# stamped on the frame match the title? Any evidence of gas spillage on the tank or around the carbs? How about the steering? Will it need steering head bearings? Does it have the emissions B.S. on it? How's the inside of the tank? Side covers have the correct emblems, no cracks and all the rubber mounts are in tact on the frame? I think it would have to be in fabulous condition before I'd pay that much for an SR. Yes, the SR is our thing and I'm sure we have that much in the 78 and in the bodywork we've collected, but that's mainly for sentimental reasons. Then there are other maintainence questions. When was the last oil change, the last time the carbs were gone through and cleaned. Does it have stock carbs or have larger carbs been put on it? Why does your friend want to sell it?
Send a PM to Mellvis if you'd like more info. He's a great SR guy to talk to.
Take care and good luck!! Let us know if you get it and make sure you get lots of pics. I'd kinda like to see it anyway!!
Abbie