Ferrets make wonderful pets. I too work 9-5, but they are straight out of their cage as soon as I get home and they sleep in my room (free roam) at night time in a box stuffed with jumpers. They also go for walks on harnesses to optimise their health and happiness. Their diets are relatively simple, I feed mine proper ferret kibble that contains 36% protein and mix this with either liver, hearts, egg yolk or mince, all raw as they get the nutrients better this way and it doesn't mess with their digestion.
They are very easily entertained too, they love playing with a blanket and being dragged across the floor, they jump in the pile of plastic bags that i store behind my door - they also nap there too. I recently found mine playing with the toilet brush and stuffing themselves in the tube and rolling around in it which is super entertaining for me as well as them.
Although they are great in pairs or more, if you're only going to get one then make did you're ready for the commitment. They are very loyal and will see you as their caregiver, so if you're to get one on its own, a lot of one on one play time with you is very much a serious requirement if you want a happy pet. It's still a requirement if you have more, but having more than one means that when you're busy, the pair can keep themselves entertained with one another with play fighting being their main source of fun.
Even if they're good as gold in the house, you need to keep a protective eye on them, just like you would with a child. They get into places that they shouldn't (like under my sink!), they investigate absolutely everything and may find themselves in trouble. Toilet lids should be locked at all times, same with the shower as they can fit into spaces you wouldn't even believe. Wires should be out of reach, and make sure that there are no obstacles that will help them get to a high place that you can't reach to save them. It sounds like a lot of work, and to be honest it definitely can be, but the outcome of watching and interacting with these furry, cute and crazy pets is a huge payoff. They are lovely and with time and patience, they'll become your best friend, just like a dog would.
As for pricing, I couldn't tell you as you're in USA, but I'll list it anyway in case I can help someone where I live.
Ferret kits (babies!) - About £10-£15 depending where you look. They're usually on pet selling websites (pets4homes, Gumtree etc) from people who live in rural areas. I don't know of any pet shops that sell them like they do in America, but i'd much prefer to buy/adopt one from a private seller anyway. I've also seen a few ferret rescue centres online for somewhere more Southern than I am, so if you can adopt, then that would be awesome, there are far too many abandoned animals that need loving homes. I rehomed my guys through gumtree by a lady who just couldn't take care of them as she was allergic.
Neutering - £45, so to have my 2 boys neutured, it'll cost £90. Bargain!!
Check ups - I think this entirely depends on the vets in your area. The best vets in my town only cost me £15 for a check up on both of them. Who, by the way, are very healthy and happy!
General vaccs - Again, depends, but I think mine are about £25 per vaccination, so really not expensive at all! Obviously depends on your budget and if you have money to spend should there be an emergency or sudden illness, so bare this in mind when thinking of taking on a ferret.
Other than that, I can't think of much else. Any questions, don't hesitate to ask!