I, for one do like custom guns, have alot of them, some built on CZ actions... & $200.00 is a very reasonable price, if the custom work was done by a qualified person... if the workmanship is awefull, then it's no value at any price...
my suggestion, is to put it next to a manufactured gun of similar style & compare them to each other... it's very possible the custom rifle could be nicer than guns 4-5 times it's price, but also could be a cobbeled up piece of crud... you should be able to tell by comparing it with another known "good" rifle.
.243 was not a stock bore, so the barrel had to be replaced, does the barrel look nice, is it blued nicely ??? or is it duller & just "blackened" ??? if the blueing doesn't look nice, it could just have been cold blued, & could come off / look worn very easily... it could also be duracoated or some other "paint" type coating ( that's not necessarliy a bad thing )??? does the stock look nice ??? or is it dented & beat up like a reshaped milsurp stock ??? how is the trigger??? tougher to pull military trigger, or does it have a smooth crisp breaking trigger like it has been replaced with a nice adjustable aftermarket trigger ??? bolt handle bent or straight ??? of coarse this type of work could have been done from any varrying degree, from a hack job, to a beautyful custom rifle... best way to tell what you're looking at, is to directly compare it to a known "good" gun