Imo, most of those cards are unplayable anyways except for Unlimited (seriously, who plays that anymore and even then a good bit of your mentioned EXs suck in unlimited anyways), so if you're not a collector or don't want to try selling them on ebay or something, I'd say that's an ok, if somewhat one-sided trade. I mean, Blissey will be around for the next 2 seasons, so just consider it an investment into the future. Of course, you probably could have gotten more too.