Own a set of Dillon 308 dies, but I came across a used set of Forster 308 dies for a good price. Both would be FL sizing and no micrometer seaters. Waste of money to pick them up as well?

The first question would be, why do you need another set for .308?

If the Forster die set includes their Bench Rest seater, then I would encourage that you buy it for that reason alone.

Forster is my first pick nowadays when buying new dies. Their Bench Rest Ultra seater is the best I own. They have a company policy that for only $10.00 and round trip shipping costs they will custom hone any of their full length sizing die necks to any dimension their customers want. This to me is huge. You end up with custom dies tuned specifically for the brass you use that won't constrict the neck any more than needed. I have a .223 die set up by them with a .2445" neck. I can barely feels the expander ball as it passes through the neck.

That dimension is the absolute largest I would go for .223. A .243" neck would be the smallest I would consider. Dillon power trim sizing rifle dies are the very worse I have ever used as far as creating too much neck tension. It's ridiculous how much they squish the case necks. I own RCBS, Redding, Forster and Hornady die sets and can't say a word bad about any of them.

I use Dillon seater dies on my progressive presses because they allow you to disassemble the die while still in the press without loosing the seating depth setting. This is a huge advantage when loading lead bullets. Lead and lube build up over time when loading these projectiles. Being able to pull a cotter pin to fix it is a Godsend.

Dillon rifle dies come with a carbide expander ball. Dillon FL sizer is more like a bastard child of a FL and and Small Base Sizer Die.

The Forster charge is not $10 but rather $12 to hone a FL Die.  
When forster did not have their bump die line up this was good value.
But, now with the bump die it more cost effective to buy a bushing for the same price rather than a dedicated die or two.

The Forster decapping rod had the expander ball higher than other brands do.  I think this is an aid to minimizing runout.

Forster does not offer a wide range of cartridges.  And, the good thing is the pricing structure of Forster is stable from main stream to odd ball.
The only gripe any one that I know of has ever bitched about is the paint on the Ultra Micrometer Seater die.