Mark, most of the time you will not notice the difference between 133 and 300...unless you are shooting several images consecutively....I try to stick with the higher write speeds...30ms to 50ms just in case I do want to burst several images....I use PNY Pro UMDA and Sandisk extreme III to IV cards...I have read too much on card failures from memory off Ebay...I have not experienced it yet...however, my thought is why chance loosing the data for $10 to $15 dollar difference......You can alway find a deal out there...I think you may like this link from the buy/sell area...
Sandisk Rebate
Hope this helps a little....