I recently purchased a PT 908.
There are Mags on Auction Arms. Here: http://www.auctionarms.com/search/auctions.aspx The 10 round ProMags appear to be extra long. I don't have any of those.
There are also a couple listings on Gun Broker.
Even Taurus lists them on their site, but I haven't checked with them, yet. Here: http://www.taurususa.com/accesories-magazines.cfm
Even Cheaper Than Dirt lists factory mags for them. Here: http://www.taurususa.com/accesories-magazines.cfm They ain't cheap, but they are O.E.M.