8 port gigabit switch with real vlans and link aggregation. only web based though (can be a plus or a minus)
around $100; total 100
small nas with iscsi/nfs - only 1 10gb nic though
add $200; total 300
2 3tb disks
add $300; total 600
NICs should be purchased as a bonus as vlan capabilities on the switch should be more than enough for a lab - but here are some contenders. I can't think of spending more than $50 per port; quad ports are more expensive than 2 dual ports and should only be considered when no more expansion slots are available (for example in shuttle machines). Remember to check the motherboard for exact pci express port capability. Plus, expect to work a bit on making drivers work on the non Intel and Hp.
i'd buy a couple dual ports, so add $100; total 700
for the actual hosts, an i7 with 32 gb ram and hopefully 2 gb connections in mb, in a very small form factor. These look nice enough. The older h67 is about $100 less in amazon, which is a big deal.
2 of those, add $500; total 1200
2 i7 8 core cpu's. Check thoroughly on the virtualization options offered by each processor. I would take a "faster/cheaper" one and another with "more virtualization features" so you can see the differences (remember ti match the motherboard to the processor and features, since both have to support them).
2 around $300 each; total 1800
64 gb of ram (8x8gb). It's the main thing that limits your environment, don't lose your time with less. If you have to go down on budget, compromise elsewhere.
Around $400; total $2200.
And that's it. You should have one of the best labs you can imagine. You'll need 2 4gb usb sticks to install esxi, network cables, a good surge arrest/ups, cheap keyboard, monitor, and a laptop from which to control it.
SSDs is prob overkill for a lab but if you have the money, i would setup a new nas with SSDs.