Tooth 14 and 15 are missing and I can't afford implants, would dentures be a good option?

Dentures are not the best option, but if finances are an issue then that would be your best choice.  You could start there and if your financial situation changes in the future you could switch to dental implants.  Good luck.  

If you are not able to afford cost of dental implants, cheaper options available are removable partial dentures and adhesive bridges. The are non-invasive and treatment time is shorter than dental implants
Please discuss these options with your dentist to see if these meet your needs
Dr Oke 

As yr primary concern is cost, so best option for you is dental tourism india. you will save upto 70% on total treatment costing with same quality treatment. Dental tourism is very popular for dental implant and cosmetic procedures.  

Are you also missing teeth on the right side? If you are, then a “partial denture” to replace all the missing teeth in both sides. Now, if you don’t have any missing teeth in the right side and only with #14 & #15 missing on the left, then partial denture will not work. It won’t fit stable enough. If that is the case, you can talk to your dentist about a 3-unit cantilever bridge (12-13-X), but with that option, you’ll only get one molar (#14) back.

A partial denture is a like a can opener which will cause you to lose more teeth over time. Save up for the implants. In the mean time, have your dentist make you a upper and lower clear retainer like an Invisalign retainer which will keep your teeth from shifting.