Quick Domain Question.

I don't think the hyphens will make any difference. I think where that would matter is when people type your domain name into the search engine, they don't type with hyphens. You will loosed a number who have been there before, but don't remember to put the hyphens in. That said, they will find it when they search google for your domain without the hyphens.

if you want to target both howtobuyanelectricguitar and buyelectricguitar, your can do either. The shorter the better though in my book. You will get the howtobuy people with just the buyelectricguitar if you have content on your site that uses the howtobuy phrase pretty often.

Maybe it's the choice of names, but electricguitars.com would cost you a fair chunk of change. Assuming that's beside the point, here's what I believe:

1- The longtail keyword will catch the long tail searches. Normally, if money were no object, you'd buy the best domain possible (electricguitars) and use the more targted "how to buy" domain as a feeder. The longer domain will have to struggle to gain a slot near the shorter domain, but the longer domain is also targeted. Somebody looking for how to buy back scratchers is a better prospect than someones searching for just backscratchers - though the latter will get more searches. That's just my opinion.

2- Regarding, hyphens, I am on more solid ground. Hyphens have no effect on your search engine ranking. On top of that, electric-guitars.com would be a lot cheaper than electricguitars.com. The minus point is that your customers may forget the hyphen and end up at your non-hyphenated competitor's site. Also, the domain itself will have a lower resale value, if that's a concern. All in all, IMHO, hyphens can be real bargains for site developers.