Are there rules and guidelines anywhere for loot in D&D 5e?

Question

My players are used to playing RPG's on PC and love getting new weapons and loot. I can't really find much in the PHB or basic DM guide.
I have been using http://redkatart.com/treasure5e/treasureGen.php up until now but it seems to only give gold and gems, and I would like to be able to make custom shops with randomized inventories to add a little flavour to my towns.
Even just a run down of equipment milestones players tend to need by certain levels or explanation of the whole "masterwork" weapon systems would be fine. Just something so I don't give them the "Sword of 1000 Truths" at level 3 and accidentally ruin the balance of everything.

Answer 1

Unfortunately, we won't see these guidelines (unless part of them show up in the previews), until the DMG.

So I can state confidently, that these rules do not exist in official published materials.

For now that treasure generator looks like a pretty solid option.

With respect to creating your own shops, unfortunately, the economy is based around magic items being rare enough that they are incredibly hard to both purchase and sell, so I'm not sure we'll see a list of shop inventories in 5e. The best I can do there is that the starter set has some guidelines on what mundane items shops in Phandalin have.

With respect to recommended items per level, again this is advice we simply don't have. But it's worth noting that in general items we've seen don't have levels. That doesn't necessarily means they wouldn't be overpowered for certain characters and underpowered for others, it just means we haven't seen levels attached to them. We have seen +1 attached to weapons and armor, so certainly you wouldn't want to give a L1 character a +2 or +3 weapon/armor, but beyond that the guidelines are non-exisistant at this time.