Can you pay for a visa to enter Laos at the border?

Depends which boarder you go to

Yeah I paid some guy in an office in udon 3000 and he sorted it all out and even took me across in his car to my hotel (only in Vientiane) and offered to pick me up to bring me back, I forget the name of it, hoping someone else might have used it and can say what the place is called.

You can get a visa on arrival at Laotian borders. I believe it's $40 in very crisp new US dollars without any marks or anything, or if you want to pay baht it will vary from 2000-2500 baht depending on the staff of the day.

Be aware that the visa takes up an entire page of your passport.

Some of the borders also have digital visa on arrival available, so if you know which border and at least 3 days ahead you can apply and pay online and then don't have to wait in line at the border, plus you'll only get a small sticker in your passport instead of a full page stamp.

Yes you can apply for e-visa or buy a visa on arrival.