Simple, how much would it cost points and/or cash (£ if possible) to purchase every costume for every character?
Ask the OP
$15.00 on Steam
I got mine for $7.49 when it was on sale.
The full pack will set you back £10.99, €13.99 or $14.99. You actually save quite a bit from buying the complete pack, if you were to buy all of the Costume sets individually, you’d pay about £35 for it instead. Definitely a good deal IMO.
EDIT: This is on Steam. I have no idea about 360 or PS3 DLC, as I do not own those consoles.