Ive been trying to use the pawnshop to my full advantage. People keep saying that they trade the bot, put in the right amount. Itll say its not neough, they overpay. it says dont overpay. is this user error or something on yalls end? Do i need to input different amount for sale? buy?

I believe it is best used for the credit system.

The Credit System

You could pay for an item with credit in place of metal if the owner of the trade allows it. Our credit system is a direct 1:1 exchange of metal and on-site credit, without taking any fee. You could access the credit interface from the top menu. The credit interface let you deposit metal for credit which subsequently could be used to purchase items on Dispenser.tf.

The credit system is not 'essential' for trading on Dispenser.tf, but it rewards you with convenience and advantage if you have credit in your disposal:
'Pawn Shop' accepts credit or metal as payment, but the former would provide better convenieny.
You almost always need credit for 'Offline Purchase', unless you keep everything under your shop inventory.
Credit is convenient for paying .11 or .22 refined metal, it helps you in situation that you could not craft metal in game.

You could withdraw metal with credit from the site anytime. However, only Refined Metal is available for withdrawal: If you have '1.11' credit, you could only withdraw the 1.00. The .11 could not be withdrawn until you make another 1.00.

Using Pawn Shop

You may come across a number of 'Pawn Shops' operated by VIPs. They work a bit differently to normal trades. Instead of 'Purchase' and 'Offline Purchase', there are two other options. 'Purchase from Shop' let you purchase whatever items that are available from the shop. Pawn Shop accepts both credit and metal as payment. You must first input the amount of items you are going to purchase before initiating the trade. 'Sell to Shop' let you sell items to the shop for credit. You do not have to explicitly specify the item and amount. You can sell items to the shop as long as it has enough credit to buy your items and you are selling within its limit.

http://dispenser.tf/s/faq/basic/

Any weapon is kinda broken. It allows you to trade once, but only a single weapon. After that you have to reload the page and trade for a single weapon again. From what I tried I assume it only looks at the 'first' weapon and the amount of that, but not at every weapon the seller has putt available for trading. So if you want to buy 20 weapons from a pawn shop and the pawn shop has 20 different weapons, you'll have to trade him 20 times and reload the page in between every trade.

I assume the same goes for other 'Any' trades.