Cutting overmats is not hard, but you need a good jig. I use a simple Logan device that sells for $90 -$100. Some remove the rubber feet to deal with the deflection in the 1/2" base. I added second base of 3/4" plywood to increase rigidity. Make sure you use the jig on a surface that doesn't have much give in it.

Seal presses are very good. I used to have a Bogen Technal press that was also quite good. Look for used equipment in good condition and you'll save about half what a new one costs.

Good luck.