Right now I have an Acer X233H 23" monitor. I've been looking into getting another one and setup dual monitors but ran into some problems. Conveniently the X233H seems to be discontinued and I haven't found one site that sells it new for under $200. I think I originally bought mine for $140 a year ago and feel weird paying $200+ for a discontinued monitor...
Newegg does still sell the 22" X223W though which is reasonable priced at $130. But the resolution on it is 1680 x 1050, where as my current monitor is 1920 x 1080. They are almost identical in design and have the same stand but I still have a feeling it's going to bother me. Has anybody had experience w/ 2 different sized/resolution monitors? What do you think?
I could also sell my current monitor on ebay and buy 2 new monitors. It seems monitors have decent resale value on ebay but I've never sold through it before and don't really want to deal with shipping
you can use two different sized monitors side by side however as you suspected there are a few issues to consider. you will not be able to fullscreen across both monitors completely. text will appear to be different sizes. icons, etc might not be the same size and line up perfectly with the left monitor. overall though possible i'd suggest two monitors of the same resolution, brand, and model. the only mis-matched size option i find usable is a small screen for computing and an lcd tv for use with movies (use as a copied desktop).
if you cannot find your model i'd suggest either doing as you said and selling your monitor, buying two matching monitors. or you could get another 23" monitor at the same resolution and try using that. keep in mind that the base heights might vary so you might have to shim them to line up the screens.
as for selling your monitor: ebay is decent but you will have to deal with paypal. shipping is tacked on to whatever the final bid amount is. the only thing to remember is to post photos and clearly state return policies. if you dont want the ebay thing then try craigslist and sell local.