Looking at Amazon's top sellers in desktops, the first entry with a tower and a non-sucky CPU was #14, Lenovo ThinkServer TS140 70A4000HUX i3-4130. The barebones version was $235.
I clicked 'buy' on that about five minutes after starting my search. Hard to imagine a more careless decision on my part... but how far wrong can one go buying a Thinkserver? Nobody ever got fired for buying IBM, even after they were sold to Lenovo, right?
It arrived promptly as usual. Here's a picture of the inside:
The case is great. There are flexible no-screws-needed carriers that slide in and out for two hard drives; it's the slickest system I've ever seen. (You do have to supply your own disk cable, but you can just recycle one from an old computer. And if you want more than two internal drives, you may have to work harder to mount them.) Nice touch: it has two front panel connectors for external hard drives.
I recycled an old 64GB Intel SSD for the system. Ubuntu 15.04 beta 2 installed uneventfully. Oh, man does it boot fast.
Moving a btrfs /home drive from an old system utterly failed - lots of "INFO: task btrfs-transacti:2296 blocked for more than 120 seconds." messages - so I gave up and reformatted it with ext4 and was happy.
Here are some benchmark results for the i3-4130 (vs. the e7300 it replaced):
I measured time to build Wine without and with -j4:
$ sudo apt-get build-dep wine $ apt-get source wine $ cd wine1.6-1.6.2/ $ time debuild -b -uc -us ... real 23m31.221s user 21m25.264s sys 1m14.884s $ dh clean $ time debuild -b -uc -us -j4 ... real 12m15.822s user 38m5.952s sys 1m56.456s12 minutes to build Wine ain't shabby. 'Course, that's how long it took in 2008, too, but Wine was smaller then :-)
For comparison, on my five-year-old i7 920 running Ubuntu 14.10 and btrfs, the same builds took rather longer:
$ sudo apt-get build-dep wine $ apt-get source wine $ cd wine1.6-1.6.2/ $ time debuild -b -uc -us real 35m46.976s user 33m1.168s sys 3m55.429s $ dh clean $ time debuild -b -uc -us -j4 real 13m42.491s user 41m22.856s sys 4m14.683sThat's right, the new i3 beats the old i7.
And here's the result from a new i5-4460 running Ubuntu 14.04 (and gcc-2.8):
$ sudo apt-get build-dep wine $ apt-get source wine $ cd wine1.6-1.6.2/ $ time debuild -b -uc -us real 21m44.769s user 20m1.008s sys 2m39.749s $ dh clean $ time debuild -b -uc -us -j4 real 8m12.016s user 23m25.585s sys 2m46.650sThe i5 took about 2/3 as much time time as the i3 to build Wine with -j4.