Is such a thing available in Bangkok? terrasil is one I used before but not bought in Thailand, although you can get it online. Is there something similar here?

Terrasil, no.

What type of ewarts do you mean i.e. genital or other?

In Thailand you can get Aldara cream (imiquimod), used for genital warts and also several preparations for regular skin warts that contain salicytic acid and lactic acid. Collomak being one such brand name.

not genital, small ones around my neck. Will have a look for Collomak thanks.

If no success, can have them frozen off with liquid niotrogen by a dermatologist. If you are in Bkk, Dr. Parichat at St Louis is good and price very reasonable.

Went to ask for the price of aldara in the local pharmacy yesterday: 210B for 250 ml (For 1 plantar wart that would come close to 10000B for a 2 months treatment).

So, better first try all other possibilities suggested here. Salicytic acid and lactic acid seems the cheapest and most obvious one.

My experience is that electrodesiccation and curettage of the wart has a higher success rate than the use of liquid nitrogen, but I don't know if they would do that on the neck.

You're going to laugh, but duct tape :

http://www.ncbi.nlm.nih.gov/pubmed/12361440

Went to ask for the price of aldara in the local pharmacy yesterday: 210B for 250 ml (For 1 plantar wart that would come close to 10000B for a 2 months treatment).

So, better first try all other possibilities suggested here. Salicytic acid and lactic acid seems the cheapest and most obvious one.

My experience is that electrodesiccation and curettage of the wart has a higher success rate than the use of liquid nitrogen, but I don't know if they would do that on the neck.

that should 250 milligram, not 250 ml