By “retreat center” I’ll assume you mean one of the various “boutique” style mini resorts which also operate as Yoga and holistic health venues. As with any specialized accommodations in Bali, they can run the whole gamut of small “mom and pop” villas to full on 5 star luxury types of resorts.
Most of these type of places are concentrated in the Ubud area, although some can be found in other areas of Bali.
I know of a modest villa style “retreat” villa along the Ayung River on about 30 are of land which recently sold for 3.5 million US. With land in that area now selling for close to $100,000 US per are, even the most modest of retreat resorts is going to be a significant investment.
“Also, would that qualify as a PMA Company to become resident?
Your question seems to suggest that a foreign investor in a PMA company automatically acquires “resident” status, but, that is not the case. In order for the foreign investor in a PMA or PT company to obtain a work permit, and legally work at the business, a KITAS, or residency visa is required.