I also bought two sets from eBay, not sure it same seller though. Mine were £29.99 a set. Both were faulty and I got string wear from the frets in a couple of days. The 'G' were almost impossible to intonate, I was never happen with the compromise.
I made a return/ refund request and they were set back at sellers request. They're in transit now and I'm promised a full refund the seller has told me of £59.98. He also told me they had had problems with the supply in the past, but with other items, not bass strings, but as a precaution, until my strings are checked against Elixir strings, he has removed all his bass strings from sale on eBay.
EDIT: I'd Emailed Elixir first about the strings, and they recommended I contacted the eBay retailer. Never had a problem like this, and it takes 6 months of hard playing to get fret wear on the string, on my basses. Used these stings for almost as long as they've been out.