How much would it cost for a small 3x5 tattoo of this?

It will vary from artist to artist honestly. One other thing to consider is detail. If you want it to look photorealistic I would go a good bit bigger. Upwards of almost double that size. If doing it that size, then you will loose a lot if detail in the vines flowers and guitar. More like a traditional style of it. Simple stuff. Reconsider getting it bigger to add real detail if you want it the way it looks.

It is impossible to say. Usually tattoos are priced by the hour. This tattoo, of just the guitar and flowers not the background, would take a few hours, depending on the skill of the artist. You should take a higher quality version of this to local artists in your are and see what they would charge you.