Water filter *Joins the ranks of ppl /w water sys probs* :)

Hi guys,
Been perusing the site here and seems really cool and informative. I came across it doing research on a problem i am having. heh maybe H2O_Man can help.

Which BTW Thank you to all the ppl out there helping selflessly.

Kk, I have apparently, an Amazon Gold model water filtration system from Rainsoft.
My issue is that i have neglected it for a bit and sadly i think i messed sumin up in the process. The alarm goes off constantly. I at moment have about 200lbs of salt in the container and the alarm goes off still thinking that i only have 50 pounds in it.

I haven't changed the filters in a long time *blush*
and am trying to do so now. After researching... it seems i have 2 choices.. expensive or more expensive heh.
apparently there is a product
TFC-RS9-22
and
TFC-RS9-22 GPD
those are the filters that match the model i have which is:
Reverse Osmosis sumin or other Model # 9596
The filter system #22GPD
Im not sure which filter i need to but or is either ok?
they both state that they are compatible with my model.
As far as the rainsoft filter system and the alarm... it gets really annoying to hear the beep. Is it sumin i fried due to lack of salt in there for a month or so? or what should i do?
Thank you again for all your help in advance.
~Carlos
I have pictures but i dunno how to embed them in here...

Oh yeah! The whole point... is there a cheaper place to maybe get these as opposed to like 40 dollars each? thank you again.