Note 5 - Stockholders' Equity (Detail) - Options outstanding and exercisable, by exercise range (USD $)	9 Months Ended
	Jan. 31, 2013
Options Outstanding at January 31, 2013	235,750
Options Outstanding, Weighted-Average Remaining Contractual Life	6 years 200 days
Options Outstanding, Weighted-Average Exercise Price (in Dollars per share)	$ 4.28
Options Exercisable at January 31, 2013	138,583
Options Exercisable, Weighted-Average Exercise Price (in Dollars per share)	$ 4.26
$3.01 - $4.00 [Member]
Options Outstanding at January 31, 2013	135,000
Options Outstanding, Weighted-Average Remaining Contractual Life	5 years 138 days
Options Outstanding, Weighted-Average Exercise Price (in Dollars per share)	$ 3.61
Options Exercisable at January 31, 2013	102,833
Options Exercisable, Weighted-Average Exercise Price (in Dollars per share)	$ 3.72
$4.01 - $5.00 [Member]
Options Outstanding at January 31, 2013	25,000
Options Outstanding, Weighted-Average Remaining Contractual Life	9 years 109 days
Options Outstanding, Weighted-Average Exercise Price (in Dollars per share)	$ 4.35
$5.01 - $6.00 [Member]
Options Outstanding at January 31, 2013	65,000
Options Outstanding, Weighted-Average Remaining Contractual Life	8 years 21 days
Options Outstanding, Weighted-Average Exercise Price (in Dollars per share)	$ 5.17
Options Exercisable at January 31, 2013	25,000
Options Exercisable, Weighted-Average Exercise Price (in Dollars per share)	$ 5.26
$7.01 - $8.00 [Member]
Options Outstanding at January 31, 2013	10,750
Options Outstanding, Weighted-Average Remaining Contractual Life	5 years 222 days
Options Outstanding, Weighted-Average Exercise Price (in Dollars per share)	$ 7.05
Options Exercisable at January 31, 2013	10,750
Options Exercisable, Weighted-Average Exercise Price (in Dollars per share)	$ 7.05