Main char is on moon guard and price of BOEs is way too much. I want to start farming old content like TBC or Vanilla for BOEs. Anyone have any good guides or know of any specific dungeons/raid trash to farm for BOEs? For example, in TBC I’ve been running Mana Tombs on repeat massive pulls hoping for any BOE I don’t have collected.
NOTE I AM NOT ASKING FOR GOLD MAKING ADVICE! I want to get BOEs for my collection of mogs 
old kara is a super raid like but its once a week
botanica is another good spot
Honestly, it’s mostly just RNG. All of the dungeons and raids will have a chance to drop stuff. If there’s a specific item you’re after, you can look it up on Wowhead and they’ll show you where it drops with the highest droprates to help you out.
It’s all just RNG. Check out where the BOE drops and farm that. Basically, farm the instance until the 10 run lockout kicks in, then take a break, or do a raid, then rinse and repeat.
The best advice is to build an ally speed druid for this kind of work.
I meant that while you can target them, depending on where you go, it will obviously be RNG if they drop. 
I thought you can get like any BOE from any dungeon in that entire xpac? like if I run Mana tombs or botanica its all the same?
Oh, you’re talking BOE world drops. Sorry, I missed that.
In that case, instances are probably a bad idea. Better to find some place with high density, kill early, and kill often.
With world drops, most everything has the same lousy chance.
I’m talking specifically instance drops from the trash in the dungeon… but I’m open to farm spots in open world too? 
avoid open world farming
there are to much variables against you then
Not if the area is quiet. There can just be a lot of downtime with instances. Minimally, there’s the 10 instance limit. With a fast character, you can blaze through an instance faster than 6m, which means you’re stuck. If you can find someplace that respawns behind you, it never runs out. With only one player, its almost impossible to trigger a hyperspawn, which is what you really want for this sort of thing.
Any recommendation on a WOTLK dungeon?