If you want to be in the business of offering payment services that accept Bitcoins, then you want to be able to do this underwriting. People will be a lot more willing to accept Bitcoins if you can say 'the value of BTC fluctuates relative to USD, but we guarantee that we will always buy them at this exchange rate. If you use this exchange rate for setting your prices then you will never suffer from these fluctuations'. To be able to do this (and not make huge losses), you need to be able to influence the market price by buying and selling in large quantities and by avoiding selling when the price is too low. Having a large initial stash of Bitcoin helps with this.
Maybe you're not looking very hard. Typical incandescents get 16 lumens per Watt, CFLs get 60 lm/W. That means that your 100W incandescent would generate around 1600lm, and you'd need a 26W CFL for equivalent. That's not a round figure, but 25W is and a 10 second search tells me I can pick up 25W spiral CFLs which are about the same size as an incandescent for around £5.
I was actually a bit surprised by those numbers (maybe Wikipedia is wrong?), because I found that the light level increased when I replaced a pair of 100W incandescents with 18W CFLs around 10 years ago. I mostly now buy 12W ones, because they're cheap and the fact that they're much brighter per Watt than incandescents means that I can put them in lights that are only rated for a 40W bulb and have more of them.
That said, I started using CFLs about 16 years ago (largely because I got tired of replacing bulbs). The first generation ones were noticeably dimmer after 2-3 years (but had already paid for themselves in energy savings, so were just demoted to lamps that didn't want to be as bright). The first ones died after 5-6 years. Since then, I've not bought a light fitting that doesn't comfortably fit a large CFL bulb. Most lampshades do, so it's only the smaller free-standing ones that are a problem. I like the Japanese-style ones that are a vertical cylinder of paper and these will happily take CFLs that are brighter than 60W incandescents, but won't take anything hotter than a 40W incandescent.
Only if you've got a really old printer. Remember, DOS predates abstraction layers and clean printer APIs. You print from DOS by opening the serial or parallel port and sending some data over it. If you've got a DOS program that can print to PostScript printers, then you're better off printing to a file from DOSBox and then printing the result from the host OS.
That said, there's little reason to use most DOS business applications these days. There are typically open source alternatives that are far better as they aren't written with such tight resource constraints in mind and can reuse GUI toolkits and so on (again, remember that DOS programs had to come with their own embedded GUI system and for most of them 4MB of RAM was a lot - a modern program can use more than that for the window buffer). I still occasionally fire up the Psion Series 3A emulator in DOSBox (if you tweak it a bit, it will run at 640x480) and use the spreadsheet though, because I've not found another one that's as easy to use with just a keyboard and constantly moving my hand from keyboard to mouse becomes annoying.
The cost of feathers has risen, even down is up!