Ok. We're straying into the business side of things here and that's a whole separate can of worms. I'll go ahead and apologize ahead of time if I seem harsh - but business is harsh, and that's just how it is.
First off - Facebook means next to nothing in a business sense. Well, slightly above nothing. A booker or party planner might look to see how many people like your page, and if that number is really high, that's a good thing. But the numbers for Facebook have little to no relation to reality. You might get 100 people to say they are going to attend your performance and only have 5 show up. You may have 5 people say they are going to attend and have 100 show up. The number of people on the page saying they like your stuff rarely has any real relation to who actually shows up - and that's the number that the people who hire you care about.
If your business cards don't have your contact number on them, they are kind of worthless.
So, here's the deal with business cards. They're a paper campaign. Just like sending post cards to everyone in a certain ZIP code - they are a sort of shotgun blast hoping that someone remembers you and decides that you're the solution to their entertainment problem. But paper campaigns, statistically, have about a 1% return rate. Which means if you give 100 business cards, you can assume you'll get 1 inquiry to your services. Note: Inquiry, not booking. However, if your business card is well designed (ie: it reminds people of exactly who you are) and it has your proper contact information, that percentage changes dramatically.
I would never go into a bar and work tables for free. For one, you can't be certain the owners want someone to do that. I know, I know, "We're providing free entertainment! This can do nothing but help them!" No. Stop it. Any good bar will have a distinct idea of what they want their bar to be. If you come along shoving cards into people's faces, you may not be in line with what they, aesthetically, want their bar to be. That means if you just walk in and start doing tricks you could be burning that bridge to the ground before you even develop the most remote of business relationships with that establishment.
You absolutely, 100%, need to talk to the owners or managers before trying to be an entertainer there, to prevent them hating you. And keep in mind, business owners in a certain area all talk to each other. If you piss off one, you are raising red flags to anyone they talk to, too.
If you want to perform at a bar, then take a group of your friends and perform for them. If someone else expresses interest in what you're doing you can try to do some stuff for them. Understand that you might actually get kicked out for this.
Pricing! If you go to a bar, and you perform for free, and they like that you're doing that - what's their motivation to ever pay you? If you say, "Ok I'll keep doing this if you pay me X$", then they can just say, "Well, no. We were doing just fine without you, thanks." Done. Not only that, if you go out and perform for some time for free, you create the reputation for being a free performer. It's very difficult to raise your price from free. Most likely you will have to ditch all of your existing places to perform and find all new ones who may be willing to pay you. You may get some patrons of the bar who think you'd be good for a party - but when they sober up and actually look at what it costs to hire a magician, that becomes the real work. You have to convince them you are worth whatever you are charging.
If all you want is experience then arrange parties and perform there. That's largely what I did. It's super easy, "Hey guys, I put together a show. I'm going to throw a party in 3 weeks, we'll have BBQ, beer, and me and Kyle and Shawn are going to put on a show! It'll be great! You should come." Done. I've packed 60 people into a one-bedroom apartment for this kind of thing.
In regards to undercutting others: You said there's very few professional magicians in your area. That's not relevant, really. You have to think about both the magic world as a whole, and also your future prospects. When I lived in Fresno it was full of magicians. Tons. There were a lot of guys who would do a birthday party for $100, and try to pack on 4 in a day. I was one of the most expensive performers in the area, and I lost a lot of gigs because they didn't want to pay my fees. They thought we were all interchangeable (because most of them were), and simply went by price. The people who saw me perform live knew what I was offering was not the same, cookie-cutter, birthday-clown magician that most people were offering and paid the fees I requested, because they knew they couldn't get this show anywhere else.
If you establish a reputation as someone who performs free, or cheap, you will have to break that reputation before you have any chance of making real money at this. Furthermore, anyone else who comes along will be fighting your established price point to book a gig as well, even if you'd never imagine trying to be booked for that gig.