A really good bargain for a 48 port switch is the Cisco 4948-10GE.
You can pick them up used on eBay for $850 or so. This is an old but well proven design with enterprise class features such as dual redundant hot-swap power supplies, hot-swap fans, full layer 3 wire-speed routing capabilities, advanced protocols(BGP, HSRP, VRF, OSPF, etc.), top-notch VLAN support, two 10GE uplink ports, full Cisco IOS operating system with software support until Feb 2014, 136Gbps switching fabric, and powerful SNMP management.
You can also pickup the non-10G uplink version (4948) for around $500-600 that has four SFP uplink ports supporting optical connections.
The EX2200 is a great switch for an all-gigabit layer2 switch. The 48 copper + 4x SFP ports model can easily be found for <$1K, and the 24 + 4 model for $600-$700 brand new. The EX3200 is a nice switch too, but the layer3 capabilities aren't worth paying more for if you're not going to need them.
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