A P06 is actually the exact same ECU as a P28, but it's missing the VTEC parts on the circuit board. The way this works is that the circuit board is all the same in that entire ODB1 Honda family, as are all the base parts. The P06 is the most basic in that family. Add the missing lockup solenoid drivers and you have an automatic transmission ECU. Add the missing VTEC parts and now it is a P28. Add the missing knock sensor board to that and you have a P30. It's very modular and a great design, they just leave parts off depending on the engine it will be used for.

It is possible to add the parts to turn it into a P28; I think Xenocron does that for $30-40. You'll also need the ECU chipped to run the proper (P28 or whatever) program after that, but you'll exactly end up with a chipped P28 when you're done.
Whether you want to spend the money is up to you, but I'd say do it. Having it converted should still be cheaper than buying a P28 and you'll end up with the exact same ECU in the end, and it will be chipped so it's ready to be tuned using whatever tuning program you want.

P06s are nice like that because you can get them really cheap, and automatic tranny ECUs can be converted to manual really easily too, both programs are already in the ECU and you just need to change a few jumpers to tell it which program to use.

*I just checked Xenocron and the the kit itself (just the parts) for VTEC conversion is $19. So you should be able to get someone local to add the parts for cheap.