i bought 3 of the 5-rounders from classic. they cost $8 each and are made in taiwan. they function perfectly in all 4 of my romy m-69's.
century also sells replacement/spare magazines...again, the taiwan made version. i believe these go for $10 from century.
almost any rings made for grooved receiver .22 rf rifles can be made to fit by removing about .040" of material from the clamp. this allows the clamps to grip the more narrow (8mm/.315" iirc) romanian receiver groove (3/8"/.375" is standard on american .22's).
tapco's website has an impressive section on the m-69. everything from bolt disassembly and maintanance to refinishing it are covered.
sure, the romy isn't an anschutz or cooper, but it sure is a fun and accurate sub-6 pound plinker. for $59, you can't go wrong.