I did the same. 30 day visa on arrival, extended once and got an LTR 10 year vise. Used Siam Legal can get full details on requirements for an LTR visa online.
I recently bought a condo. Paid to the developer by bank transfer in stages from my bank to theirs. In the middle of the process I got a Thai mobile phone and opened a bank account with the developer stating to the bank that I was buying. Have just been approved by ID for a 10 year retiree visa (LTR).