Recommendation for Lan Switch

Hi Experts,
We are looking for PoE & QoS switches as a upgrade for a LAN of 50 users. it is quite confusing while judging only by the prices or brands. For example, here are some I got from CDW:
HP PROCURVE 2520-24 POE SWITCH:         $1,000
D-LINK DES-1228P -24 PORT POE SWITCH:    $460
D-LINK DES-3828P -24 PORT POE SWITCH: $1,650  

Why is HP Procurve 2520-24 double more expensive than DES-1228P? Even within D-Link, why is DES-3828P triple more expensive than DES-1228P? Can someone help me understand what makes this huge difference in price?
We kind of preper the HP Procurve 2520-24. Is it a good one?