Upvote:0
For many of us (depends on your passport country), arriving at an airport in Thailand you can get a 30-day non-renewable single-entry visa for free. Arriving by land, it's 15 days instead. For many trips, there is no need to get a visa in advance. BTW when arriving, you will see a "Visa on Arrival" sign - ignore it, and go instead to the passport control desk, where they will stamp your passport with the visa stamp.
A little-known fact for New England folks: there is a Thai Consulate office located above Union Oyster House in Boston. They can often issue a visa while you wait, including types you pay for that last longer.
Business visas are harder to get, because the meaning is different. My company wanted me to have a business visa for speaking engagements, but I often could not get them. "Business" means working a job in Thailand, or sales to Thailand. A "tourist" visa is sufficient if you are representing a company at a conference or other presentation, so long as you are not negotiating sales.
Upvote:2
There is no etched in stone on the number of Single Entries visas you can apply for. It is really up to consular officials to determine you are visiting or living under the radar.
As you have reasonable gaps between visits you should be OK.
Upvote:2
@Tom is correct. There is no written policy affecting how many Single Entry Tourist Visas (SETV) you can obtain.
In practice, each neighboring Thai Embassy/official consulate may have soft limits on how many [consecutive] SETVs they may issue. Having 20k THB equivalent as bank statement + proof of onward travel (POOT) may help when applying.
When arriving at the border, having 20k THB equivalent cash or traveler's check (and possible POOT) may help on the 3rd+ arrival. Do NOT assume that ATM will be available.
Penang, Malaysia, Vietamine/Savannakhet Laos are friendly neighboring Thai official consultes for a quick, consecutive SETV. Have fun and enjoy your trip.
Do double-check to see if you can obtain METV. Might make life a little bit easier and flexible. SETV is good fallback though.