What instruments are required for IFR training? Just a VOR instrument?

I've been looking around for some cheap trainers that are IFR certified, but I don't know the first thing about IFR training yet. Some claim to be IFR but only have a single LOC. Ideally, I think I would like to have LOC, LOC/GS and ADF, preferably DME (not many out there when you search <$30,000). For instance, this would be great... if the overhaul was included.

Just curious of your opinions, what's required, preferred, overkill, lingo such as "Full IFR," and ways to save, etc.

Thanks