Lian-Li has released a new Mini-ITX enclosure, and it is reasonably affordable.
The case measures in at 200 x 275 x 242 mm, and because it is fully made out of aluminum, only weighs about 1.6 kg. Internally, beside the Mini-ITX motherboard, users can mount CPU coolers up to 90 mm tall along with PSUs and GPUs up to 210 mm in length, though you will have to account for connector length with the PSU in case of modular power supplies. An ideal graphics card for using in this case would be the Mini-ITX cards from Asus or MSI. Larger cards like GTX 780's or R9 290's won't fit, as they are too long.
Lian-Li has fitted both the bottom and front of the case with identical hard drive support, where each of those areas can house either one 3.5" drive along with a 2.5" drive, or two 2.5" drives. This allows for up to four installed drives. A fan can also be mounted at the bottom of the chassis, though, which might be preferable considering the only other case ventilation would be provided by the power supply.
Front I/O connectivity is fairly standard with the standard set of HD audio jacks and two USB 3.0 ports.
Pricing for the unit is set at €50 over in Europe, with no official word on U.S. availability yet. Hopefully, it'll be under about $70 when it gets here, as that'll make it a very nice option for a mid-range compact gaming system.