I was unable to get an O.G. sample from my first batch in the carboy (tried using a long siphon tube with my finger held over one end...), so I'm trying to buy a wine thief to take final gravity, but most seem too short for a 5 gal batch in a 6.5 gal carboy. I saw homebrewsupply.com sells a simple, $5 plastic baster. Any reason why this isn't a good solution? Or suggestions for finding a wine thief that's more than 12 inches long? Thanks for helping a new brewer!
I used this wine thief when I was using carboys - http://www.northernbrewer.com/fermtech-wine-thief
I also used a 6.5 gallon carboy for primary fermentation, and all you have to do is shake the thief up and down briskly to pull up more liquid into it if that's what your problem is. This method will be effective even if the thief doesn't touch the bottom.
Basters work well if you can find one that fits. 50ml pipet is basically the same thing but with accurate measuring. In a pinch a clean section of Beer line works, submerge then cap with thumb.
About your OG, fear not there is math for that if you have a FG from brix refractometer and hydrometer. The Formula is rather ridiculous by hand (honestly never seen it other than in source code). This calculator is in beersmith and the Android app Brewzor Calculator. I've tested it on several documented brews with an accuracy of 0.001+/-.