Platinumtel is the best out there they have a plan where you buy mins and they have a unlimited plan so you can get which ever works best for you here check them out Prepaid Wireless Cell Phone Service, Pay As You Go - PlatinumTel and here you can check them against other services Cheapest pay-as-you-go prepaid cell phone plan - PlatinumTel Wireless

What type of plans do they have and where are they available at?

I can't think of any with unlimited incoming, depending on where you are i would suggest maybe simple mobile, page plus, or tracphone if your only going to be using the phone to talk but there are all kinds of prepaid company's out there i'm sure you'll find one that fits the bill

My wife has a mobile which she doesn't use much to call others or text or web. She uses our home phone to talk. She gets occasional incoming calls from me or others + very rarely uses it while on road. She's on t-mobile prepaid plan. Im looking for the best deal - something like - pay 30 bucks unlimited incoming, 50+ minutes outgoing, with a very long expiry date (say 3 months or so).

Is there a provider who offers prepaid plan similar to this? Please let me know.

Thanks a lot.