Collage painting

I recently completed this 9"x12" collage painting.  Can you tell who inspired me?  I'm utterly fascinated by

Lynne Perrella's

work.  Could stare at it for hours.  Her work makes me shake.  That shaking feeling is what made me realize that I wanted to be an artist.  Nothing but art makes me feel that way.  It's like being seduced by a new lover.  Back to the painting....  This actually began as an experiment inspired by one of

Jane Davies

techniques where you dip a pipe cleaner in ink and feather it across the page and then scrape various colors of paint over the top with a credit card.  Great idea!  All my attempts looked like crap.  Sigh.  I put the papers away for a while and recently dug them out to see if I had any ideas.  The I took another look at Lynne Perrella's series based on Geoffrey Chaucer's Canterbury Tales and some ideas took off.  Stencil's and tar gel and t-shirt transfer paper, oh my!  It was great fun and I'm really happy with it.

Quandary

I completed these three mixed media paintings several months ago.  They are large....19 x 23 inches.  The base is heavy bristol paper and I've painted and collaged the surface.  There are some slightly dimensional elements too.  Here is the quandary..... how do I mount them for display?  I can't afford to frame them because they are so big.  They need a deep frame because of the dimensional elements.  I've been reading about mounting works on paper and the experts seem to think that gluing them down to a support devalues the work.  I don't even know if these are good enough to worry about devaluing them!  There is new art district developing in my neighborhood and they are putting out invitations for artists to display their work.  These three pieces are among my few finished works of art and I'd like to see if they would be accepted for display at one of the venues in our new art district but before I can do that I have to get them ready for display.  I'm considering gluing them to masonite but then I wonder if I should use some kind of varnish to protect them?  They have a few layers of gloss medium already but some of the collage elements are just plain printer paper which is not archival and I'd like to protect it as much as possible.  What is an affordable and reasonably professional way to finish these pieces?