Get a cheap bass guitar (Harvey Benton are Chinese Fender eh... inspired designs, but they are prefectly well for starting out and cost <100€ new, even less used). Then get yourself Rocksmith 2014, either on PS3 or PC (if your PC is capable of last-gen games). It's like Guitar Hero but with a real instrument. You plug in the bass to the PC or PS3 with a special cable. Your PC will also act as amplifier and effect chain. Then the game will pick up the notes you play and give you visual feedback on hit or missed notes. There are also tutorial videos ingame that go over basic playing technique. Of course there is slowly rising dynamic difficulty and the whole shebang. It's a very cheap entry and tons of fun. And you ARE actually playing. So the muscle memory you are building is real, don't think of it as a dumb game.
Of course there is no substitute for a real teacher, but if you can't afford one, it's the closest you'll get. If you can run the PC version, there are also thousands of user made song charts so you'll never run out of new songs to play (http://ignition.customsforge.com/