Why an evaporator AND compressor? If the evaporator is leaking, the compressor should shut off with the low pressure and not fail due to lack of lubrication.
Get a second opinion for sure, and have them show/tell you what the issue is. If they use a sniffer down the vent make sure the fan isn't blowing. There should be a sticker on your core support saying how many ounces the system takes. It's best to put the system in a vacuum if it has been opened up, and you'll need to add an appropriate amount of PAG oil to the system when you replace components.
You're not apt to spend the $xxxx (four digits) for an A/C machine, although you may find one used for $500 in quasi-working condition.
I was a subaru mechanic at a group with a dodge shop down the street, and we ended up getting a truck traded in because of A/C issues - the guy put in an aftermarket compressor, evaporator, condenser, and several thousand bucks worth of labor (at the dealership) and then traded it in because they still couldn't solve his issue. I found that the new compressor was leaking out the shaft.