Currently am in very nearly exactly the same predicament- First time I took the window switch cover out, I didn't realize how they popped out, and I broke the tab off the first one and the one ont he passenger side was so brittle that when I took it out I ended up snapping that one unintentionally as well.
Everyone on Ebay wants about $50/ea for those pieces... Best bet is to go to a local scrap yard and ask if they have vans around, that's what I am planning on doing. If the scrap yards don't have these, at times you can find people parting out vans... but you have to be really quick to get the parts you want... chances say someone else wants the same parts.
What I have done in the interim is cut up a painters stick and epoxied it on as temporary. The fit isn't immaculate, but it doesn't pop out by itself, either.
About the overhead light that turns on with the door- YES, there are other types of lights. I have one in the "trunk" area of my van that looks like the spitting image of that, except it has an "on/off/door" switch. It seems like it was OEM. There are also the "reading lights" that have the on/off/door positions (they rotate, its not a physical switch) that would likely accomplish the same thing.
While you're contemplating the doors... I've been thinking about changing to 2009+ doors myself. The switches are different, but I believe the interior door panels match up exactly, so you can fit the new interior on older vans. Personally, I like the aesthetics and practical storage on the newer door panels, and as soon as I can get my hands on a pair of interior panels, I will be swapping them.
Even if you cannot get the switches, there was a user on here (Very recently) that did a DIY with old switches that turned out very nice looking.
I'll see if I can't find the thread and link it here in a minute.