Pricing on property management platforms is usually per unit per month with a monthly minimum, and the minimum is what governs at 30 lots. Ranges people quote sit somewhere around $1 to $2.50 per lot per month, with floors that often land in the low hundreds of dollars a month, and the manufactured-housing specific platforms tend to sit at the higher end because they handle lot-level utility billing. Online payment processing is usually separate, either a per-transaction fee absorbed by you or passed to the resident. Pricing changes, so get a written quote for the specific lot count rather than trusting a number from a forum.
A spreadsheet does work at 30 lots for collections. Where it stops working is utility billing. If the park is master metered, meaning one meter from the utility serves the whole community and you re-bill residents, you either read submeters monthly or allocate the bill by formula. Doing that by hand for 30 lots, every month, with a defensible record if a resident disputes it, is where people give up on the spreadsheet.
The part you haven't hit yet is the lot file. For each lot you want the signed lease, the home's serial or VIN, and evidence of who holds title to the home. Manufactured homes are titled, and how that title works, whether the home can be converted to real property, and what the transfer process looks like varies by state. When you sell the park, the buyer's diligence will ask for exactly those files, and a park with clean lot files sells more easily than one with a notebook. Start the files on day one, whatever software you land on.
