The reason you pay a tradesman money to do a job, is because they've got the tools, facilities and expertise.
If you called for a plasterer, and they asked you to find him a special trowel because your walls were a funny shape, you'd be telling him to FO. Theres an expectation that a plasterer will have the stuff to plaster your walls. Sure there might be some special tools that arent used often, but i'd expect that he would know where to borrow them should the need arise.
Similarly, i would expect the mechanic should know another few mechanic mates and be able to phone round and find someone with the kit and borrow it from them.
As a DIY'er, if i dont have the tools to do a job, i go and buy them. If i never use them again, i'll sell them on, or leave them on the shelf just in case. Typically i find the savings of doing the job myself outweigh the cost of the tools to do it, and it allows me to build a collection of tools over time.
I guess you have a choice, you either buy the tool yourself, lend it to your favoured mechanic and then either sell it on, or keep it for the future, OR you find somewhere that does these cars and has the tools already.
You might find somewhere that will rent the tools out if you search google. A8Parts used to rent the tools out to do various engines, perhaps give them a try?
