CONSOLIDATED STATEMENTS OF INCOME (unaudited) (USD $)	3 Months Ended		9 Months Ended
	Oct. 31, 2012	Oct. 31, 2011	Oct. 31, 2012	Oct. 31, 2011
CONSOLIDATED STATEMENTS OF INCOME (unaudited) [Abstract]
Net sales	$ 29,761,356	$ 25,245,131	$ 82,965,659	$ 71,764,377
Cost of goods sold	19,096,841	15,910,283	54,652,514	46,234,343
Gross profit	10,664,515	9,334,848	28,313,145	25,530,034
Operating expenses
Selling	3,071,621	2,944,019	9,160,574	8,784,207
General and administrative	3,343,147	3,387,617	10,735,827	9,437,146
Total selling, general and administrative	6,414,768	6,331,636	19,896,401	18,221,353
Income from operations	4,249,747	3,003,212	8,416,744	7,308,681
Interest expense	(41,470)	(47,153)	(125,868)	(145,862)
Other income	20,110	198,317	115,782	389,647
Income before taxes	4,228,387	3,154,376	8,406,658	7,552,466
Provision for taxes	1,437,652	1,072,490	2,737,226	2,567,839
Net income	$ 2,790,735	$ 2,081,886	$ 5,669,432	$ 4,984,627
Earnings per share, basic (in dollars per share)	$ 0.19	$ 0.14	$ 0.39	$ 0.34
Earnings per share, diluted (in dollars per share)	$ 0.19	$ 0.14	$ 0.38	$ 0.34
Cash dividend per share - declared (in dollars per share)	$ 0.0725	$ 0.071	$ 0.2145	$ 0.203
Cash dividend per share - paid (in dollars per share)	$ 0.071	$ 0.066	$ 0.213	$ 0.198