Acular would be cheaper than Nevanac and is the same class of medication. Nevanac is being used as an anti-inflammatory. A different, very cheap medication that would do the job is prednisolone acetate 1% which comes as a generic. Tobramycin is not a truly equal substitution for Vigamox. However you should not need to use it for days and days. At our center we pre-treat for 1 day and then treat afterwards for 3 - 4 days, basically however long the bottle lasts. Certainly you are within your rights to request another sample bottle of Vigamox since you are having both eyes done.
At my pre-op appointment, I got 2 half-filled tiny bottles of Vigamox; 2 tiny half-filled bottles of Nevanac and 2 full bottles of Omnipred. I had to pre-treat with the first 2 for 3 days before surgery. After surgery, 1 week of Vigamox; 1 month of Nevanac and 1 month of Omnipred (tapering off each week). When I went back for my post-op appointment and talked to the doctor about the cost, he gave me 2 more half-filled tiny bottles of Nevanac, but said I really needed to fill the Vigamox and said there wasn't a good substitute and he could not give me any more. I filled the Vigamox since I needed about 15 more drops to get me to the end of the regiment. Good luck; it's a breeze!
They gave you those meds for FREE? I had to PAY at the doctors office for teeny tiny bottles of each of those two, plus a teeny bottle of a 3rd eyedrop (don't have it handy, it's an antibiotic, I think). $60 for the set of 3. Also was told to pre-treat with the first two for 3 full days.