Is there a money friendly guitar similar to the SG Standard?
If you mean more price friendly than the Gibson SG, then the Epiphone SG is what you want. Although it is much cheaper, in my opinion they are still very high quality guitars.
If you really just want the SG shape, then there is the SG Special Cherry that Epiphone do. I am afraid I cannot provide any information about how good/bad the guitar is, but it is very affordable. The sellers link is selling it at £119, which equals $190. You may have to pay a little more for overseas shipping, but it is still extremely cheap.
Hope this helps :)
if by "similar" you mean "same shape" then ya, the Epiphone SG's are one option.
ESP's LTD line has a guitar called a Viper which has a simiular yet more aggressive shape than the SG. They go from ~ $200 - $1,000 depending one which model u pick. Here's a link to musiciansfriend to check em out along w/ their price http://bit.ly/ea471n
Another thing to consider is to buy a used SG. Gibson made a bunch of guiitars with a "faded finish" which were cheaper than their standard ones. So search ebay for Gibson SG Faded and you'll see a handful of guitars priced much lower than a new, standard SG. These go for $500 - $700 or so.
There is a great brand which is called "vintage". They have licenced copies of SG, and it's so nice to play with it!! I know many people who changed pickups to gibson and doesn't want to buy original, Infact I have strat-mexico copy and I'm really not gonna buy original, because one of fender guys (working in fender, and they made workshop that day) said that my strato-mexico plays even better then his original guitar =))) So I think this kind of opinion really says something about this brand =)
So just checkout what they have