It does look like this is not going to be a functioning scope, and the advice to start over on another is spot on. Just like with telescopes, there are many options out there and you first need to define precisely what you are looking for. To do that, you need a certain amount of knowledge about microscopes. At the very least, read up on microscopes online--there are tons of resources. Figure out whether or not a low-power stereo microscope would do the job or if a compound microscope is needed. A stereo microscope is a more accessible device for kids and amateur naturalists. It can be awesome for viewing everything from coins and stamps to insects and plant parts. My wife and I have a stereo microscope and two compound microscopes and the stereo sees almost all of the use. If, on the other hand, the desire is to view individual cells, then you're going the compound route. Do you know someone who would let you use a couple different scopes and get a feel for differences? It would be like going to a star party and trying out different telescopes before buying one--always a good idea.
E-bay does have great deals out there, but look for the ones that say the scope is tested and working. You might pay a little more, but are more likely to end up with something useful.
If it's a first compound microscope and you're buying online, maybe stick to a monocular one rather than a binocular one as there's less to go wrong. With a low budget, I'd buy an old classic American Optical or Bausch and Lomb workhorse rather than something from the 80's to present. I do know that the high-end scopes of today are vastly better than the old ones from 60 years ago, but the more modern lower end school models that are available in droves are pieces of junk after they get some wear and tear on them. At any rate, make sure it has something like a 10 x eyepiece, a set of objective lenses (a 3.5x or 4x objective is great for low power views and will be used a lot more than a 100x oil immersion objective), a condenser, an iris diaphragm, and an illuminator. Later on, if the desire persists, you can get an awesome Zeiss or some such, after you know what you're doing.
If buying a stereomicroscope online, it's always a shot in the dark as to whether or not the two optical trains are properly collimated. If they are not, it will be a dog to use and unless you already know what you're doing, don't even think about trying to align the optics. A generous return policy would be very helpful in such a case.
One more thought--look over the pictures with a critical eye as people stick all sorts of random parts on a microscope in order to get it to sell. If the eyepieces or objectives are not the same brand as the scope or look to be of different vintage, that would be a red flag to me. Yes, I've switched certain objectives and eyepieces around on my own scopes, and sometimes it's fine--but you need to know that it's OK. Other times it would seriously degrade the image.
It's fun to have a microscope or two around the house. Good luck!