Forgive my resurrecting an older thread but today I picked up from Aldi a Workzone spirit level with built-in digital readout for its attached inclinometer arm. Cost was under $20. The readout is down to 1/10th of a degree and, judging by the tests I made on getting it home, it is accurate down to that level. It is robustly made although perhaps a little bulky at 42 cm long. Nevertheless it will make a useful addition to my field scope's setup kit.
There may be a limited offer period involved but you can find a description at
http://aldi.com.au/au/html/offers/2827_23036.htm