John there are alot of light up collars on ebays as last year several sellers were selling them in bulk. Lots of buyers bought them and are now offereing them singly. I have one for each of my dogs and they are really good in dark conditions - not too expensive off ebay either, you could afford 2/3 of them!
here is an example of them - http://cgi.ebay.co.uk/SAFETY-LED-LIGHT-UP-DESIGNER-DOG-COLLAR-MEDIUM-GREEN_W0QQitemZ140166368289QQcmdZViewItem?hash=item140166368289&_trkparms=72%3A1296|39%3A1|66%3A2|65%3A12|240%3A1318&_trksid=p3286.c0.m14
