Thoughts on just buying re-manufactured brake calibers VS re-building existing?

I can get re-manufactured Raybestos from Rock Auto for ~$50 or WBR from Parts Geek for ~ $90 (after core refund).
I'm calculating rebuilding at ~ $50 per caliber if replacing the pistons.
My initial thought was to buy re-manufactured for speed and simplicity.

1. Recommend re-building as a DIY or buying re-man?
2. The pistons have surface rust on the exterior inner cup areas - odds that the insides are the same and better to replace or generally able to be cleaned up and re-used thus cutting cost significantly?
3. If re-manufactured is the way to go - Raybestos VS WBR? Appreciable difference in quality?

 

Many have had good results with DIY caliper rebuilding. I haven't. It has apparently been 'just my luck' that my attempts have been thwarted by unusually rusty pistons and bores so I inevitably ended up buying off-the-shelf rebuilt units anyway. Nowadays I don't even bother with DIY attempts. But, that's just me. As I said, many have had good results with DIY rebuilding.

I've used calipers from Coventry West, NAPA, Raybestos, Centric, and various other brands and vendors. Only had one dud out of dozens. I'e not heard of "WBR" calipers, personally. But that doesn't mean anything

In calculating costs bear in mind that the calipers are quite heavy. Shipping costs to return your core calipers can gobble up any savings very quickly.

Cheers
DD