The individual X-Wing paperbacks and eBooks are currently listed for $7.99 a pop; A full set would cost you $71.91 (plus sales tax, if applicable.) So if you’re looking to catch up on the series, this is probably your best bet outside of used copies and/or the library. (Unless you already own them all, of course!)
I still wish we were seeing the series reissued as trade paperback collections (maybe if Mercy Kill sells really well?) but this is a nice way to give some EU classics a little refreshing.