1.0 and 2.0 blind power discs packs retail for about $5.00 dollars (excluding taxes) and there are two discs per pack, so approx. $2.50 per disc.
I bought a bunch of 1.0 and 2.0 blind power disc packs on a tremendous sale at TRU. I kept the ones I needed for my collection and tried to sell the rest on eBay. I sold a fair amount, but I'm still stuck with approx. 20 power discs that I, and apparently no on else on eBay, wants. In order to get the discs I needed to complete my collection (the tough ones to get, of course) I had to pay an arm and an leg and a pair of mouse ears on eBay.
I realized after that fact that even though I had saved over $100 buying the blind packs on sale, I probably spent almost as much tracking down the rare and terrain discs I did want.
I would have saved the time and the money to it took to go to TRUmand buy the packs, and the time it took to sort the discs, and the time and the money it took to sell them online, if I had just bought the whole collection from one eBay seller.
Make sure you check the price (including shipping) if you buy the whole set from one seller on eBay. I found one seller that I could have gotten the 40 Disney power discs from the blind pack for $100, about $2.50 per disc. *sigh*
With the change in selling power discs for 3.0 (no more blind packs - yay!), it practically renders that strategy useless, but if you're trying to get complete 1.0 and/or 2.0 power discs set, I would suggest a thorough search of eBay first.
Another option you might check out, if you only want a couple of power discs, is to look for a local trading group. My local GameStop has a trading box that you can search through, and if you see a disc you want, you take it out and put one of yours in. I've gotten a couple of great finds in that box!
Good luck with your collection!