i think any guitar would be good to learn on, idealy an accoustic would be best and even better would be a nylon strung classical type guitar, but is that going to hold the interest of a 13yr old boy? the advantages of a nylon strung guitar are, they have a wider neck (which makes it easier to get your fingers around, more space between the strings), they have ‘fat’ strings which are easier on the fingers, steel strings dig into the fingers and you can only hold them dow for a short while, where as the nylon strings are a lot easier on the finger tips, they are light guitars, they dont need an amp, easy to tune and maintain. Well thats the upside, the downside is you look a right plum playing one, who wants a classical guitar at 13?? he will probaly want an ibanez electric or a fender or gibson, something thats loud, and heavy and cool, so maybe middle ground would be a steel string accoustic guitar, it’s still accoustic so doesnt need an amp, volume would be low, still light but the strings are made of steel and it would hurt the fingers for a while, i say a while cos after about 3 weeks of practice you get hard skin developing over the tips of the fingers, this waould also be a bonus if he eventualy progresses on to an electric. Accoustic wise you need to take him to a store to see which one he likes and also feels comftable playing, cost wise you would be looking at anything between £100 – £300 for a good starter guitar, and like wise for the nylon strung guitar. Good luck with your choice, im sure he will get a lot out of it, i got into guitar in a similar way, i only went to school guitar lessons to get out of French lessons! i went 2 weeks and was hooked, still am 25 years later. Lee (just turned 40)