Hi, i specialise in hair extensions and you would be able to get extensions in that length hair..i have done it before a few times..pls see my facebook page 'debs hair room' for photos. However it really is a LOT of upkeep for hair your length, and you should only go ahead with it after a VERY thorough consultation to decide if you are prepared for the extra care and attention that you will need to commit too.
You wont be able to just wake on a morning and tie it back, it will need to be styled daily to ensure you own hair lies flat and covers the bonds..of which there will be a lot of. You also need to find someone with a great reputation for installing hair extensions,as if this is done badly it will really show. I put every bond in in half sizes so this takes double the amount of time,but it is the only way to make the bonds virtually undetectable and suitable for this length hair...i hope this helps..