Hi Andrea!
I started out with a 6×10 Kelsey table top press (and a Nolan cylinder press, which is a lot like a Showcard). I’ve since added a 10×15 C&P as well.
The table top presses are great to learn on and are good for things that are smaller—business cards and greeting cards. I ran a 5×7 invite on the Kelsey once and it had a hard time getting even impression across the plate. I ran it later on the C&P and it had a much nice print quality and impression. Since the 5×7 plate took up most of the area of the Kelsey’s print area, the pressure it could exert was lessened since there was a larger area that needed pressure. With a smaller surface area to print, the pressure becomes more concentrated and you can get a better impression/print. Same holds true for whatever size of press you are using.
I would consider seeing if there are any classes you can take before taking the plunge into press ownership. You can often see different kinds of presses and their capabilities before investing in press. I started my business with the Kelsey, but quickly realized for the type of work I wanted to do, I needed to get something larger. Many times the larger presses can be had for the same dollar range as some of the table top presses. The table top presses tend to go for more since they are a bit easier to move. I paid the same amount for both the Kelsey and the C&P and they were in similar shape. I actually had to get new rollers for the Kelsey, so it ended up costing me a bit more than the C&P.