My current target electronics lab (for hobby use):
1. Hot-air rework station (maybe the Atten 858D) (~$50)
2. Hakko FX-888 with a few screwdriver and hoof tips (~$100)
3. Rigol DS2000 series, or possibly a DS4000 series O-scope. Could also go for one of the Agilent 3000X series (~$800-$3000)
4. A few multi-meters (3 or 4 should be fine). Something like a nice bench meter and 2 handheld ones. (~$300-$1000)
5. Blue Rubber ESD mat (~$50-200)
6. Some kind of magnifier, either one of those desk-clamped 8" magnifiers with a ring light or one of those camera magnifiers with a monitor/PC hookup. (~$100-300)
7. Make-shift reflow oven. Either a hot-plate based design or a toaster oven design. (~$100)
8. At least 1 adjustable PSU, either home-built or pre-built unit (~$100-$500)
9. Various odds and ends hand tools like side-cutters, screwdrivers, crimpers, etc. (~$50-$100)
10. Fans or some sort of flux scrubber. (~$50-~$100)
11. logic analyzer, if I don't have an MSO (~$100-$300)
12. MCU programmer/debuggers, preferably for PIC's, AVR's, and ARM (~$200-$600)
13. Signal generator (~$500-$600)
Total: ~$2500-$7000 (not including storage cabinets, parts, consumables, and the bench/workspace).
Alternatives/splurge add-ons:
A. A nicer hot-air rework station (~$300-$600)
B. De soldering station (~$500)
C. A second or third power supply (~$100-$1000)
D. FPGA development tools (not sure about cost, seems tools are specific for each different manufacturer)
E. Arbitrary waveform generator (~$1000-$2000)
F. A very nice O-scope (for hobby use), possibly something in the ~$5k-$10k range
G. A nice microscope, possibly something like the ones Dave has. No idea about cost, but probably a few thousand.
Splurge cost: ~$20k
Something in the sub-$10k range and even sub $5k range will be a very nice lab for serious hobby use or small business use. Businesses work differently because you may need several of each to accommodate what workers you have, workers may be specialized, and you'll likely have specialized needs. Business also has many more worries than a hobbiest would have such as sourcing parts in volume, actual production costs, infrastructure, etc.