Raleigh NC agent here. Agents do not collude to increase DD fees. What we do is read the market and advise our clients on what we think will win the bid if there are multiple offers.
To answer the OP, if there are no other offers on the table, I would suggest the DD and EMD be about 1% of the price. So, if you're buying a 400k home, I would probably offer 1000 DD and 3000 EMD. The seller may come back and ask for more DD, and I'd be willing to probably go up to about 2-3k, depending on how much I want the house.
If there are multiple offers, I would considering doing 5-10k (or more), depending on how competitive I think the other buyers are, how much I want it, and what kind of condition I believe it to be in. If I'm full gut remodeling, I don't mind a higher DD because I know I'm fixing everything anyway. If the home seems to be in GREAT shape, I'll also be willing to go higher on the DD.
There was a point during the crazy sellers market we're emerging from that I wouldn't bother writing an offer with less than 50k DD. I never WANTED my buyers to pay that, but that's what everyone else was offering, so if you weren't willing to do it too, you couldn't compete. Having listings really helps you understand what the buyers are willing to do, and each of my listings would have 20-30 offers on them, with about half of the buyers offering 50k+ in DD and the other half not. The first time homebuyers were the real losers in that market because they couldn't afford to compete with cash heavy investors in the same price point.
I'm pretty sure GA just adopted the DD fee process too, so it's not JUST TX and NC. I actually really like the DD in theory because it makes our contracts VERY black and white. However, it's only good when it's a reasonable 1-2k at risk, not 50k!
