I say get rid of your girlfriend, saves you one bunch of money XD j/k (well, it WOULD actually save you a bunch of money, but I was joking about the riddance part
)
If you want to get it to just toy around a bit and cutting throuh paper, well... I guess the 20 buck swords should do it, but I wouldn't expect it to stay alive any long...
For the sword, it really depends on the thing you want to do with it. If you want to decorate your room with it, and not practically use it, I'd reccomend a sword worth about 100 bucks, because if you get cheaper ones, they might look cheap or get it over the time by oxidation or this stuff.
If you want to buy it for self defense or something, don't buy anything under $300, as you need to rely on it. Then again, if you don't know how to wield a sword, you'd probably be better off with your hands alone.
Finally, if you want it for serios sports competition, like Iaijutsu or Kenjutsu combat, get a real sword, meaning about $4000 to $10000.
I got myself swords for about 100 bucks before, the normal kind... well, the upper nail (Mekugi) broke after a while for the first one, and the hilt got pretty loose for the second one after some time as well. When I got into Kenjutsu, I bought myself an Iaito, which I'm really content with - then again, you wouldn't need to spend about $1000 if you're not swordfighting every week
Either way - a Bokuto is the cheapest option if you go for the 'first time sword fighting experience', as you can get a pretty good one for about $15 already (those take about 1000 (parried) hits, which is pretty good for a sword like that).