Does it matter ?

So I've been with my guy for almost four years! We have two kids live together yada yada right ? Well I'm kind of upset because he says he wants to marry me but hasn't got me ring. No big deal right? Rings can be expensive I know that, so that's why I went online found a CUTE cheap ring for like $20 and he's all like NO! that's too cheap im not about to get you a Walmart ring. Does that sound like an excuse? Or should I just SHUTUP and wait for him to save money for a ring? How long do I wait? Sorry if I come off as bitchy I just don't understand why he wouldn't get me this cheap ring? It's not like I'd tell the family even if my ring was 5000 I wouldn't tell! Im just not like that. Any advice ladies? Be nice! Thanks yall