How much would my system go for?

What it goes for in one country is DEFINITELY not what it might go for in another. So, what country are you in?

Typically if everything is in great working order, you can reasonably expect to get 60-80% of retail for hardware that is less than a year old.

That generally drops to 50-70% of retail during the second year. After the second year you are lucky if you see a maximum of 60% of retail price, generally speaking, and you may have to sit on your hardware a while trying to find the right buyer if you want to leverage any of these sales into those upper figures. Amounts will of course fluctuate and you can expect to get less for anything that is aesthetically damaged or dingy.

Also, you aren't going to sell anything by saying you don't know anything about the hardware. It makes a difference. 32GB of plain Jane Crucial memory isn't going to bring even a fraction of the price of G.Skill Trident Z memory, for example.

You need to take the time to find out as much as possible about each and every component, including approximately how long that component has been in service.

Well, if you're in the US, then the prices suggested by ravenjedmanicdao aren't even REMOTELY close to what you'd see here in the US. They have an ENTIRELY different commerical landscape when it comes to consumer products and especially electronics in Australia and New Zealand.

Many products are almost impossible to source down there OR are 2 to 3x more expensive than what you'd see them go for here or in places like the UK. I would certainly not gauge the resale value of anything based on that.

Here in the US, assuming mid tier quality for unknown products, you could reasonably expect to see between 500 and 700 bucks IF EVERYTHING IS IN TOP NOTCH condition, AND if it includes a decent motherboard, which I do not see in your list of parts.

That does not include the keyboard and monitor. For those two items, I'd say you might be able to pull in between 350-400 dollars IF they are not worn, with no goofed up, worn out or broken keys on the keyboard and no issues whatsoever on the monitor including no dead pixels, no burn in (pretty rare these days), no persistent lines, cracks, blotches or other visual corruptions, no buzzing and no shut off conditions.

All together, as a package, I'd think that MAYBE, IF you found the right buyer, you could probably pull in 800-900 bucks for the whole shebang, but that's assuming everything is in perfect condition AND you find the exactly perfect buyer who is willing to pay top used prices.

Normally, you cannot sell complete systems for as much as you can sell the parts individually for. In reality, I can pick up used systems much like yours, complete, for about six hundred to seven hundred dollars, WITH a motherboard. Sometimes a bit less, sometimes a little more, but on average, someplace in that area. Of course, that does not include any shipping, insurance or special packaging considerations.

Typically, those you have to either eat or split with the buyer, because they can almost always find something similar at least relatively local to where they are and not have to pay to have anything shipped at all OR find a similar system on Ebay that the seller is willing to pay shipping on.

Being as I buy and sell hardware regularly, but not on a regular basis, as it's not what I actually DO, those are just my opinions. Others might have slightly different opinions. Generally, I think it's pretty accurate especially since graphics card supply has seemingly caught back up with demand and older cards are not pulling in the kind of prices they were a month or two back due to the bitcoin craze anymore.