Cat with gastrointestinal intestinal problem

My 6 yr old female cat, Sassy suddenly starting having hard stool & was constantly straining to make a bowel movement. I took her to our vet where I was told she was constipated and needed an enema. Sassy stayed overnight because they had to use anesthesia. Anyway, I was told she had to start eating a specific food. They sold me an 8 lb bag of Royal Canin. The bag cost me 33$. I have 2 other cats at home and once they got a whiff of that food they basically won't eat anything else. I've tried feeding them in separate rooms, at different times but now they just won't eat their own food. Is there any type of food I can feed all 3 keeping Sassy healthy without the overwhelming prices. I do not haves the funds and would never consider giving any of my 3 cats away. PLEASE HELP!

[opus88]

hi Simba I am not a Vet and I have very different views of nutrition than most Vets do. first of all the Vet you saw IMO is entirely wrong to give you a bag of dry food, ANY DRY food is not good for cats...esp. with bowel or urinary tract problems...(esp males). Your kitty needs to be on a wet food to help him with his constipation issues...this is a must!!!!

I will give you a link to reading up on cat nutrition and the evils of dry feeding..be free to ask more questions anytime.
this Vet promotes raw diet, however if you look on the right hand side you can click on 'commercial diets' for names of good brands of can foods. but remember if money is a huge issue, ANY canned food is an improvement over any dry food...♥

http://www.catinfo.org/