Low cost touchscreen with decent performance?

Looking at putting in a touch screen to control some functions (those will be on a raspberry pi but I don't think that matters).  7 or 10" seems like a reasonable size - big enough to see and operate fairly easily and still keep the cost down.  Not interested in really cheap junk.  Android tablets seem like a good way to go.  Budget isn't fixed but am thinking $100 or less.  Is this reasonable?  Should I consider refurbished? 
 
Have considered a small LCD display and keypad like this:
 
http://www.adafruit.com/products/1115
 
but seems like a touchscreen would be well worth if for a better display and not having to write custom code to drive the LCD/keypad.

A couple of years ago here played with a Mimo USB connected monitor. 
 
Worked fine with a Pogo Plug (well Seagate Dockstar) shortcutting some by using standard LCD drivers / touch stuff.
 
I have been able to purchase new commercial small POS touchscreens with VGA inputs for less than $100.
 
Not sure if these would work with an HDMI to VGA conversion cable.

There are hundreds of inexpensive 7" Android touch screens available.  Here's a good list.
http://www.amazon.com/s/ref=sr_st_popularity-rank?keywords=android+touch+screen+tablets&qid=1401756016&rh=n%3A172282%2Ck%3Aandroid+touch+screen+tablets&sort=popularity-rank
 
The last generation of the Kindle Fire tablets are a very good touch screen for the money.  I use a couple of these with HSTouch and they work very well.

today only
 
http://www.newegg.com/Special/ShellShocker.aspx?cm_sp=ShellShocker-_-34-758-004-_-06022014_5

Sero 7 pro

Newegg has a shell shocker today on a hp slate 1800 7" tablet for $32.99 after a $30 rebate and a $7 discount with code "MASTERPASS10".