During tuning a new set of strings, my top E string snapped.
My colleague says that you have to buy a complete set of strings because it does not come alone and every set have its own frequency so:
In England, at least, every guitar shop I've ever been in will sell individual strings. A good job too, as I use an unusual combination of gauges, meaning I'd have to buy three sets to make one for my guitars. So, yes, they are available, maybe you can buy 10 of each gauge on the internet; one individual from a shop. However, a set won't break the bank, and you only need to use the same as you broke - then you have spares.
It's also very dependent as to how old the original strings are. If you broke one while fitting a new set, obviously you wouldn't put a whole new set on. But if the set is quite old, rusty, or sounds dull, then yes, change the lot.
Yes - you can buy individual strings for guitars.
Typically I do keep a couple of spare E-strings in case I break one during a performance, but generally I replace all 6 at the same time
So if your strings were new and you just broke the top E, yes, I'd suggest just replacing it.
If you break the top e string during installation of a new set, you can certainly buy a single e string. There is no need to buy a whole set if the strings you did not break are all new.
I shop at Just Strings dot com for individual strings. Here is a link to their single guitar strings page Single Strings at Just Strings
Here you will find single strings from many of the major manufacturers in various gauges. Try to pick one that most closely matches the one you are replacing in composition, type, gauge and brand. The high e string is a plain steel string so most brands will be interchangeable. Just get the same gauge as the one you broke. Or you can get a different gauge if you prefer.
Some local guitar shops might carry a selection of individual strings as well - and you will save the shipping costs. When I buy individual strings on line, I buy several because there is not much difference in shipping cost between one string or ten strings.
I buy single strings because I like to choose each gauge of my sets individually. I might have heavier bottoms for more base and lighter tops for easier bending.
Also, I like to keep a few extras of the strings most likely to break. In addition to the thinnest high e-string, a wound G string is very susceptible to breaking as well. The reason is the steel core (where the tensile strength comes from) of a wound G string is actually thinner in diameter than the high e string. So next time you hear a guitarist complain from the stage that their G String just broke, you will know they are not trying to be funny. It was most likely the g string that broke.
If I break a string on stage, I can't take time to change an entire set and I don't like to rob a full set just to get one string because then when I go to install that set it will be a string shy of a full set.
Good luck with your next install. Be sure to stretch your strings gently after installation. Also, if your string breaks near the bridge - check to be sure there is nothing sharp on your saddle that might cut into the string. And tune the high e up very slowly.
You can put any combination of strings as you see fit. There is no need to have a matching set. I have known guitarists that use sometimes two and three of the same strings and just tune them differently. It's all about the sound you are looking for.
In theory you should replace all strings with a new set, in order to maintain the same degree of aging in all strings.
As Bayley already stated in his answer, older strings need to be more stretched to be kept in tune, and metal strings (you don't specify which type of guitar and strings you are talking about) oxidize wich gives them a different tone coloration.
So if you replace only one string, you mat get differences in tone and tension that may harm your playing.
Having said that, I too keep getting my 1st string (high E) breaking, both in my electric and acoustic (folk type) guitar (specially since my son started using them regularly :-), and if I would change all strings every time it would be a small fortune.
Some string manufacturers provide sets with an additional E 1st string, so you can keep the same set while changing the E string once. This seems like a good compromise (remember, you should change all your strings anyway every so often, as they become dull and harder and harder to play).
But if you break your 1st string once or twice a month like my son does, you can buy just the one string. It's not easy to find in the suppliers but it can be found, or order directly from China through ebay. I've ordered 10 pieces each (~5$ for 10 strings) of 1st strings for electric and folk guitar of the Alice brand and I'm quite happy with them (for practising and home usage).
If you go that route, some degree of difference in tone and playability is probably anavoidable, but to minimize that be careful to buy the same gauge as the one you're replacing.
Dude, its like $11 bucks. Just buy the new pack. But to answer your question, no i have never seen individual strings for sale, with the expectation of some very low guitar tunings.
When replacing the E string its best to also do all the other strings as otherwise you will have tuning issues if only the newer string is stretching.
