Craig's list has no substantial limit on ads, but if they are worded the same in different categories, they will possibly deny you. Their ability to differentiate is through some pretty basic scripting.
Owner/Dealer is not particularly policed, either. If you are selling as an owner, and you answer the phone as Gilly's/Eddy's Appliance, the customer will think you are a scammer. Hello does it. I don't think that there is a charge for dealer ads, so it kind of depends upon your schtick.
I became an appliance tech by becoming an appliance tech. Literally. I had a great example from my dad, he fixed everything, and never paid anyone else to do it, so I knew it could be done. I had three other service businesses, so I knew I could get people to pay me (housecleaning, hauling, and handyman). I moved to a location that I thought would have lots of handymen, so I decided to specialize myself by being an appliance guy. And I did just that.
There were times that I did not even know how to open up the darn machine. But instead of looking stupid (I hope) I would take the model number, and say I was heading back to the "shop" to "pull a manual." Basically, I was going home to look on google, youtube, appliancejunk, and others. Then I would go back, figure out what was wrong, and fix it.
Sometimes it cost a lot in time, sometimes a lot in parts, but I really made fixing it the priority, and money the secondary. If I messed up, I kept at it until I figured it out, being that a successful fix was the goal, not the money. After all, I wanted to earn money by FIXING appliances, not by charging for telling them to buy new.
I learned a crap-load. I also, to my knowledge, do not have a single customer that is pissed off at me.
Five years later, I am happy, confident, successful in my business, and, to be honest, looking for the next challenge.
My best advice for the beginners is to understand what the machine wants to do, what it needs to do it, if everything is right, then you can find out why it is not doing what it wants to do.
So, to get heat, a gas dryer needs electricity running through outlets, power cords, timers, start switches, thermostats, thermal fuses, ignitors, gas valves, possibly a motor switch, etc. So you follow the electricity. Outlet - check. Cord plugged in -check. Timer engaged check. Door switch - check. and so on. Pretty soon you know that you go first to the thermal fuse, because that is most common. Or, if there is any heat at all, most of the electrics are ok, so look at coils, air flow, or cycling thermostat. Sometimes the knob is just broke.
You really don't need to know the brand in order to begin, but you do need to know the theory of operation, and that will tell you almost everything except the computer stuff. I mean, even a solar clothes dryer needs a heat source, air circulation, and exposure for the clothes to transfer the moisture from the cloth to the air and take it away. A solar dryer uses the sun as a heat source, natural air currents to provide circulation and pull moisture away, and it spreads out the cloth, both vertically and horizontally, to provide maximum surface exposure. (A solar dryer is a backyard clothesline.) A gas dryer uses gas to provide the heat, a motor to turn the drum and tumble the clothes, providing maximum surface exposure, and a blower wheel to circulate the air and pull the moisture away. Plus some safety devices to keep the gas and electric contained: timer so it doesn't keep going forever, thermostat to regulate the temperature, valves and burner to direct and contain the flame, thermal fuses to turn it off if it gets too hot, etc.
They both essentially dry the clothes the same way, but to speed up the process, add convenience (drying in the rain or at night) and keep the whole process under control and safe, it gets a bit more complicated. But it is still understandable, predictable, diagnosible, and repairable.
I could give you the same theory analogy between a squaw beating buckskins against a rock down by the river, and a Samsung frontload washer (or even a Bosch dishwasher for that matter - a squaw beating fine crystal against a rock to get rid of water spots...). Or a neanderthal toasting bits of rodent meat over a fire compared to a Viking dual fuel range.
Heck, I could even draw you the appropriate comparisons between a backyard clothesline and a Sub-Zero built in Reefer. It'd just take a bit longer, and I'd have to explain more things to get you there. The refrigeration experts on this board would know exactly what I'm talking about and could probably do it better than I could. For example, both your freezer and your clothesline have an "evaporator." They both actually have a condenser, too, but we don't care about that for the clothesline, 'cause its an open system (just sayin').
So it all will make sense if you understand what the machine wants to do, how it goes about doing it, and what the operational, safety, or vulnerable points are. If you get that down, you can start to fix most anything. I have done a wild variety of non-appliance stuff just from that type of understanding, a bit of internet search, and the experience I've gained so far.
If I can do it, anybody can.