Hi Ana,
What steps have you taken so far to heal the fissures? Most doctors will recommend a step-wise approach starting with diet changes and stool softeners, and then working up to nitroglycerin cream or a calcium-channel blocker, botox injections, etc. When all else fails, LIS surgery is certainly an option, but it's usually a last resort.
The cost of surgery depends on a few factors, such as exactly what type of surgery is being done, where it is performed (hospital or office) and what type of anesthesia is used (general or local).
My surgery (LIS / hypertrophied papilla removal / skin tag removal) was performed in my doctor's office with local anesthesia and it was less than $1000 (I'm in California). Surgeries performed in the hospital under general anesthesia can get very expensive.
I would recommend that you do lots of research on the colorectal surgeons in your area and see what you can find out.
I wish you all the best!