Income Taxes - The tax effect of temporary differences that give rise to significant portions of the deferred tax assets and deferred tax liabilities (Details) (USD $)	Apr. 30, 2014	Apr. 30, 2013
Deferred tax assets:
Compensated absences and severance, principally due to accruals for financial reporting purposes	$ 75,000	$ 150,000
Stock-based compensation expense	1,275,000	1,259,000
Accounts receivable, principally due to allowance for doubtful accounts and sales returns	86,000	78,000
Property and equipment, principally due to differences in depreciation	240,000	106,000
Intangible assets	430,000	464,000
Inventories	68,000	91,000
Domestic net operating losses	10,134,000	9,089,000
Alternative minimum tax	438,000	438,000
Other	153,000	61,000
Deferred tax assets	12,899,000	11,736,000
Valuation allowance	(12,899,000)	(11,736,000)
Net deferred tax assets