Yeah, they have gotten expensive. They have fancy ones and basic ones... but even the basic are pretty spendy now. I had the same problem as you and put one in (years ago) and it was a godsend for working on the engine
, just open the hatch and crawl in there... daylight helps to see things very well!
I see from your pic that it is hinged... and it also has all those screws huh....? I would think the hinge would keep it from sealing well on that side. Do you get any leakage now? You could install a bunch of T bolt dogs
on the inside... if it's possible to reach them. Maybe one on each end and two on each side. Wouldnt be super handy but better than undoing all those screws..
There used to be some bronze ones from taiwan
that were inexpensive and used a simple T bolt and very secure hook arrangement. Cant find them, but they were a simpler, more secure version of this: