What is the cheapest way to fly to Vientiane for an education visa, and is it normal for a school to ask students to go there?

More than enough options as travel advice. Have a safe trip and good luck.

Assuming you're in Bangkok, the best way to to take a 6am flight from DMK to Udon. This can be booked in advance for as little as 500b one way. Then take a van to the border (200b) and taxi to the consulate (300b, less if you share). As the process takes 2 days, you can take a late evening flight back the following day. So with a bit of planning you can get there and back for well under 2500b

It is very typical to make education visa runs to Vientiane. Most foreigners living in Thailand can not easily get to Savannakhet. Vientiane is easy to get to through Udon from DMK or UTP (cheap flights and cheap taxi) or directly (more expensive). Van rides for most take 12 hours. If you arrive at a time and day in Vientiane that they are not busy, it is not horrible. The busiest days for arrival are likely Monday and Thursday mornings when the minibuses make their group visa runs. You may wait a long time if you arrive early in the morning. You will wait less if you arrive at 11:00. It is usually a 2 day process. Leave documents one morning and pick up visa the next afternoon.

Haven't done it myself but may in the future--from what I've seen, it looks like the cheapest way to fly would be to go to Udon Thani, take the bus to Nong Khai, and cross the border there. Flying directly into Vientiane is actually quite pricey, I think because they restrict the airlines that can fly there.

Immigration at Vientiane is horrible... Should go to savannakhet, its easier!

I went there for my Ed Visa. It is simple and straight forward.

One thing that was stated on a sign there and on my queue paper was, "You must have an address in Thailand " It would be a good idea to be prepared for it.

There is a hotel across the street from the Thai Consulate called Douangpraseuth Hotel located on Rue Bourichane Rd.

Not the cleanest place but low budget and great location.

Good Luck

Here is a screenshot of my notes from my education visa run to Vientiane. Has everything you need

The school can recommend a Thai consulate, just because they know the procedure there and know which documents the school has to provide to get it all done smoothly. The cheapest way to get somewhere is using google, we are not a travel advice page.