Was the XR750 ever available to the general public? I mean could I have on in to the dealer and just bought one when they were being built, or were they just for racers? Has anyone seen one for sale?

I think anyone could have bought one.

Only for sponsored competition.

http://www.hi-speedmotorcycles.com/index_files/Page448.htm

'it's only money', right?

Only for sponsored competition.

That is correct,some were sold to privateers but it was race only bike and never seen on showroom floors sor sale.
The last time I saw one for sale localy was 10 years ago at a swap meet in Oregon and it was at a dealer's booth.
$7000 and it was in rough shape but I was I'd of bought it because they are very price these days.
There are two on cycletrader online right now by the same seller,a 1970 iron XR750.
these looked like an iron sporty motor.
they want $28,900 for this one.
http://www.cycletrader.com/caddetail.html?/ad-cache/5/3/5/85859835.htm
and this one a last year made 1980 alloy XR750 in need of assembly.
they want $19,950
http://www.cycletrader.com/caddetail.html?/ad-cache/5/3/6/85859836.htm

You can buy a complete XR750 engine out of the screaming eagle catalogue.Don't know how much.

The XR-750 was last sold as acomplete bike by H-D in 1980. Any body could buy one. At one point you were supposed to have an AMA license. This was a joke. A sponsorship? No.

After 1980 H-D did not sel them as complete bikes, just engines. By that point there were many good suppliers of chassis parts. That's how it still is. To prep an XR for serious use,it must be gone through and thoroughly tweeked.

Fewer than 800 XR-750 engines have ever been made,usually in batches of about 100 every so often. The last big revision was in 1990. They went to oval ports and bigger crank pins to withstand 100+ HP and 9000+ RPM.

They had a bad batch of machining on the cases that year and it caused a lotta heartburn but was corrected. For a comprehensive history Allan Girdler's book is a good read. I had a 1975 750 which I raced and later made into a street bike. Sort of.

I beleive it is around $14,000 for the XR750 engine out the Screamin Eagle catalog. You will need to machine the engine it comes in peices.

If you want the complete engine call St Louis HD. Talk to Jim Williams. It will run you, can't be sure, either $7500 or $8500. Assembly required--$2500/$3500. Head work by Darcy, $2500. And it goes on and on. 2-3 months ago A&A Racing had 3 complete xr750s. $20000/ea. Talk to Jim or Ray.

It would take a bit to make an xr streetable. Good luck