Repairing A/C, Leaked All Refrigerant

Have a lightly used Coleman Mach that I replaced after only a couple years (It actually began dying the first year). It sprung a leak shortly after I purchased the camper, and all the make-it-cold stuff eventually came out. I've looked around and found a few pages about repairing these things. Apprently, installing one of those "saddle" valves after the repair is made almost always end up leaking. So soldering in an low pressure valve is the "proper" way to repair these otherwise unrepairable units.

I just hate to toss the thing. It has very little use. It's practically new. I'd like to at least see if it's possible, and get a few bucks for it to offset the cost of the new one I purchased.

Thoughts? Is it worth it or even doable?