We only have cell phones. For $80/month we get four phones (one for my boyfriend, one for me, one for each of his parents) and 700 any time minutes with free nights and weekends. We don't have a landline but his parents do - they just have their phones for emergencies/while driving, and to talk to us (we get free calls between our four phones). The basic plan is $50 for two phones, plus $8 per each additional phone then taxes add up to $80/month. My family is all across the country and due to the time difference I usually talk to them on my way to/from or at work, so I use the cell phone a lot ("free" long distance). My boyfriend travels for work regularly, and it's nice that we can talk to each other anywhere/anytime without paying or keeping track of calling cards or hotel numbers. Also he can call from a cab in between client visits, etc - which is great, otherwise we might never talk when he's gone! We don't have a landline, the cheapest basic-service-only landline we could find was $25/month with taxes which is outrageous.
If the church wants you to have the phones, could you ask them to cover part of the cost?
I would never pay for the phone itself - when you sign a contract (go for a 1yr if you can) they'll have some phone choices available for free, they are fine! Also ask around to find out what providers have the best coverage in your area.
They may not be the most "frugal" option but I am grateful that we choose to have them (we do not have cable TV as a compromise) because it allows me to stay in much closer contact with my family

Where to find them: many malls will have kiosks for each cell provider, or they will have standalone stores. Radio Shack sell for Verizon and Sprint (maybe more?) and other stores will do similar things too. You'll want to look into calling plans, decide if you would want one phone or two (usually a family plan includes two lines with free calling between them), figure out what features you want and don't want and check coverage areas. Then you can go into a shop and talk to someone if you like. You can also order online but be aware that if you do this and something goes wrong with your phone, you have to mail it in to be warrantied/replaced - so you'll be without it for several days. If you buy in a store you can just bring it in to a store to be replaced. We ordered online so they would be here waiting for us when we moved back from overseas and my phone broke 3 months later - it was a pain to warranty it! I would buy from a store from now on. DO NOT LET THEM pull your credit until you have decided what phone you want to buy. Ask for information and tell them you are just looking and not interested in having them check your credit at that time. They can give you price quotes without running your credit they just don't like to.
MTA: None of this takes into account PAYG phones.. no idea how they work in the US, in general I find them to be a bad deal if you use them frequently but they can be great for "emergencies only" phones.