Yes - there "can" be a BIG difference.
One gets what they pay for.
The Federal Value Pk I buy is the MP 12 ga 3dr 1 1/8 #8 shot. Good components HARD shot. I know from pattern board and actual use what it will do. IIRC I paid $13.95 for 100 rds ( $ 3.48 a box or .14 a pop) Mom&Pop gunstore...I got a free dealie to clean my glasses, a handful of Sheath Take Alongs bag of popcorn, coke and screwdriver dealie too.
Ammo, eats and toys...I like M&P places.
Normally I buy at Sports Authority or Academy Sports...better prices anyway.
The other day at Academy the Win AA Target loads - IIRC $3.69 or $3.89 ( I forget...) a box of 25 , and one can save these hulls and reload them or have someone reload for you. 3.89/25 = .16 a pop and reload hulls
I tried a box of Rem black hulled shotshells and every gun I tried , did not like them. I can't recall exactly, I can't find the one shell I have around here. High velocity and 7/8 oz. that much I do remember. I tried a 870, 1300, a H&R Topper, Kreighoff and a Citori .
Box of 20...means $2.98 / 20 = .15 a pop. I dunno they may work in your gun, have to try 'em. Often times the 20 rd box is a promo load and lost leader.
For the price of a used MEC , or buying the components, contributing toward components and letting someone reload the better hulls you may be better off...depends on how much you shoot.