You will love having designated space for your sewing machine.
Respectively, and speaking from experience, a leaf on the right side of the cabinet is needed for pin cushion, etc........I have my cabinet butted up to a chest that level with my cabinet to achieve the needed space.
I also have the plastic drop in piece to make the machine level with the cabinet. I have found it to be very wobbly and it interferes with trying to use it. Have it stored and just leave my machine up and I piece with it as it. And, mine was made specifically for my machine and cabinet. Do be careful.
All in all, for the price you are looking at and the size you want/need......I would think you could pay someone to build your cabinet with two lift up pieces....one which hold the machine (usually on the back) and one which supports that piece (usually on the front). I am trying to describe the way 'old' sewing cabinets used to look.
Good luck and enjoy whatever you decide to buy.