I wonder what the economics are here. Using his setup, you can get an Axim X51 on eBay for around $100 and the scanner he uses goes for around $250 on eBay ($384 new). That's at least $350 in initial costs.
Assuming a profit of $5 per book (just a wild guess) you'd need to sell 70 books to recoup that cost. Using his ratio of 1 "buy" to every 30 "reject" books, you'd have to go through 2,100 books to recoup your initial costs!
Taking it a step further, if you could scan three books per minute (another wild guess), it would take 700 minutes, nearly 12 hours, of "hunting" to earn back you startup costs.
Based on all those numbers and assumptions, your hourly earnings are roughly $30 per hour. ($350 / 12)
Based on a standard 2,000 hours of work per year (basically, 5 days a week for 50 weeks), this comes to $30*2000 = $60,000.... awfully close to his estimate of $1,000 per week for a person working alone.