The pen tablet is the cheaper option but it's only 1:1 ratio in the center and it varies as you move outwards so it takes some getting used to. A pen display you draw directly on the image at a 1:1 ratio across the whole screen but you have to deal with the parallax effect created by the distance between the pen tip and surface because of the thickness of the glass which some people find annoying. Supposedly the new Wacom models have a dramatically thinner glass that is also textured more like paper but I'm not ready to drop a couple racks on one. One complaint about all but the very recent tablets though is that the textured surface wears off with use and eventually looses its "tooth" and becomes so slick that it gives an undesirable drawing experience. I figured out a work around to this problem so using a med sized tablet becomes very cost effective for me.
But it's definitely not the same as drawing on paper so you might want to get started as soon as you can.
Huion makes a cheaper pen display tablet then what Wacom offers that gets allot of good reviews but a couple things to consider is that for one thing that company gives out free tablets to people in exchange for reviews and although I guess the hardware is good people have reported problems with the software and it's actually only 1080p and not 4k and if you want the 24 inch variety it's still like $800. You can pick up an Intous 5 for like $50 now if you look around on ebay and if you don't already know then I'm here to tell you that the difference between 2000 levels of pressure and 8000 levels is negligible so the race to have the most levels of pressure has already passed the point of diminishing returns after reaching the 2045 levels of pressure threshold anyway. I mean maybe if your doing some little scratchy type of sketchy shit then you might need the extra sensitivity but I don't see that being an issue for people doing graffiti type of artwork.
Just do what I do resurface it with some light sanding and wipe it down with acetone to take off any oil or crap then use the right nib.
Not that anyone cares but here's new sound collages I made... http://www.bangyard.com/music/wb/Satire - Echo the Dolph Lundgren.mp3 http://www.bangyard.com/music/wb/Satire - Get Bundt.mp3 http://www.bangyard.com/music/wb/Satire - Fuck You Very Much.mp3 http://www.bangyard.com/music/wb/Satire - Hasta la Vista, Baby (Because of the Abortion).mp3 http://www.bangyard.com/music/wb/Satire - Insane in the Members-Only Jacket.mp3 http://www.bangyard.com/music/wb/Satire - Quarter Past Eternal Torment.mp3 http://www.bangyard.com/music/wb/Satire - Rake Whistle.mp3 http://www.bangyard.com/music/wb/Satire - Szechuan Chicken Choking.mp3 http://www.bangyard.com/music/wb/Satire - The Things That Things Thought.mp3 http://www.bangyard.com/music/wb/Satire - Unusual Anomolies in the Soup.mp3