Well def get that sand out, priority and leave the UV off until you can get it replaced.
I know the best place to get the reptisun is http://www.petmountain.com
. Im not sure tho, if you will be able to mount the starter you have inside the viv
Turtle eye drops will be fine. Dont put them directly into the eye but just allow them to run over the eye (he will probably close his eye and that is absolutely fine). There is def something more serious going on with that other eye tho - it could be infected or anything. Im not sure how much a vet visit is going to run you over there - I pay roughly £25 for a straight forward check up but once meds etc become involved it can go up dramatically.
Also, what calcium supplement are you using? And how often? Are you using any vitamins?
How about temps - what are you measuring those with?
How long have you had the little guy? His situation can improve in terms of the MBD but it will take some effort.