Pay rates for a server developer?

It really depends on the developer, some like to do by task, some like to do by time, but you would need to ask them.

Personally I prefer paying by task rather than by time because who knows really how much time they're actually spending on it vs quoting you for it. Unless it's someone quite reputable I wouldn't mind paying by time.

Most reputable developers who don't want their time wasted will either do hourly + a certain percentage of the total estimate upfront (also with a contract, always do a contract), or they will charge you a flat fee generally higher than the worth of the time they are going to spend on it. At the end of the day, developers are providing a service that you need, not the other way around. We often have many other clients, and if you aren't willing to pay what we ask for our services we will just go to someone else who will. That's just how it works.

I myself would also prefer a task based payment. I try to charge a price, which in the end results in 5$ per hour, since I can determine how many hours that work will take me. You can also do time based BUT NEVER CODE LINES BASED, because the amount of code lines is not necessarly equal to the work put into it. For Example: I once made a Holocron System with file savings and stufff with about 1000 lines of code, but even a Jobs.lua of a big Server will have more than a few 1000 lines.

Just ask to pull a freeman and put everything on one line of code to pay them for only one line. stonks.

But seriously, nobody in their right mind would pay for x amount of lines of code. Hourly is for reputable developers. I would say pay on a task by task basis, but be ready to pay a hefty fee since nobody else is getting the addon, instead of your usual 5-25 dollars on gmodstore since tens/hundreds/thousands of people are also getting it