What size filter?

Sorry, forgot to mention:
Sta-Rite System 3 - S8M150

After a little research I get B&M quotes on these filters for $700+.
So Ebay ($450) seems worth a shot.

Found it for $460 on poolfilters.biz
I dont know the company.

These carts have a bad problem of being broken in shipping. I suggest you buy them locally and open the box and inspect them before purchase. It can save you a big hassle.

Well, I went ahead and ordered them through Ebay, $436.00, insurance and free shipping, it turned out to be a wonderful deal and terrific seller! Inspected the cartridges, and did not find any cracks whatsoever.
Only thing was that one of the vertical strips glue had come off. Possible because of the heat.
The stamp indicates that they were made in Dec 08. All in all very satisfied.
I have no intention mentioning the seller as I am not affiliated with them in any way. All I wanted was a reasonable price for my replacement cartridges. Thanks for the help!

How old were your filters before you had to replace them?

I am also thinking of replaceing my 2 sta-rite cartridges. Its been about 5 years. Seems like ebay is the way to go.