Bill,
If cost is a primary concern, the Dynon products are still an excelent deal even if you buy a seperate CDI.
The GRT and BM products are good. But the cheapest GRT that does HSI is $6000. You can get a D100 for $2400, and even with a $1500 CDI you're still saving $2100. The smaller, cheaper BM unit does HSI, but only from an SL30 radio, and you have to turn off the EFIS to see the HSI. Not much point in loosing your attitude, airspeed, and altitude if you need to use the HSI in real instrument conditions. To get the larger screen is at least $6500.
As mentioned before, we do plan on doing an HSI in the D100 series. This will allow you to see your EFIS and your HSI at the same time, and will most likely just be a software upgrade to the D100.