I didn't hear a guitar in either song...
The first song is running a pluck of some kind through a cabinet impulse response. You can find a bunch of free cabinet IR samples around, and there are several free Convolver plugins out there.
The second song sounds like a RhodesEP-ish sound running through distortion.
Nonetheless, a guitar is still useful to have in the production process. Buying an electric guitar and an audio interface might be your best solution. You can get a relatively cheap version of both (
guitar,
interface), and it's an intuitive instrument to play. That was my solution to the problem (I had never played guitar before). Ended up using it in my next song for a slow melody that took at least 100 recording attempts. There are a ton of Youtube tutorials out there on learning to play the guitar that I need to do here at some point (learning chords and techniques).
For amp simulations, there is the fantastic
LePou Amp Sim Pack, and if you can find them somewhere, the entire series of free plugins from Ignite Amps (I can provide them since the site seems to be down).
And for cabinets,
this is a good start.
