800gp for an encounter, operating under the assumption that this will be divided amongst 4 players will come to 200gp each. Considering the XP from this fight I think you are actually being too stingy.
I point you to the Wealth Per Level chart as others have but I will add to it with further explanation. See this clause:
Character Wealth by Level lists the amount of treasure each PC is
expected to have at a specific level. Note that this table assumes a
standard fantasy game. Low-fantasy games might award only half this
value, while high-fantasy games might double the value. It is assumed
that some of this treasure is consumed in the course of an adventure
(such as potions and scrolls), and that some of the less useful items
are sold for half value so more useful gear can be purchased.
If you are running point-buy 20 or higher, it would be 2000gp by level 2 which means you must drop a total of 8000gp for a party of four within the first level of play.
6000gp by level 3 which means dropping 16'000gp (4000gp each) for a party of four.
Level 1 flies by quick, I doubt you are going to get 10 encounters like that within level 1, so you are probably being too stingy. Factor further if it is a party of three.
The problem can come in trying to tie wealth drops to combat, it causes headaches for you and can condition your players to "Murder-Hobo Syndrome" where they see every living being in the world as just a big moneybag they can get gold from if they stab it.
Have wealth drops (gold, jewellery, valuable items) be tied to them progressing the plot, such as by finding the person who was escaping with the magical macguffin. Of course they are going to be opposed by violence and must defend themselves, but if it is more the villain trying to kill THEM to loot THEIR corpses they are going to seem a lot more heroic when they persevere and there isn't going to be as much "foraging".
Probably the quickest way to bring their wealth up is to arm and equip enemy NPCs with valuable items they might either use immediately, or sell or trade. For example, fight an Evil Sorcerer and have that sorcerer use a Metamagic Rod of Reach. It is generally a good item and casters can start using it right away and it's a lot easier to trade it with another person who has a magic item of equivalent worth.
Just getting gold and buying stuff can be pretty boring, and they may or may not search the bodies. But if they saw a magic item be used in combat or you explicitly described how well armoured they were they are unlikely to let such things go amiss.
As to your idea:
I want them to return some of the loot to the town that hired them
You have no way of knowing what your players are going to do, they could do anything, they could lie that they didn't find any treasure or under-estimate it and give only a token amount back. Even if 3 players agreed to it the 4th may think they are being suckers and won't give it up. OR they could just misinterpret what you say and conveniently interpret this isn't stolen property that should be returned.
Be ready for your players to do anything.
So you have to be ready to be flexible, if they by whatever means come across a lot of loot then fate is going to turn on them and they aren't going to get as much stuff later.
You can codify the concept of Wealth Per Level by the idea of Hubris, that "the gods" will reward the PCs with fortune for their success in their quest, not by tricks or cons or being greedy. So they can get lectures from priests and holy men that their greed will cost them in the long run, only by true accomplishment (levelling up) can they expect wealth. Spell this out to them that they don't have to worry that giving money back means its gone forever and they'll forever be behind "the gods will look kindly on them" i.e. the GM will drop something nice so you catch up.