If you just want to be losely tied and restrained then any rope is fine, however if you want to do proper shibari and eventually add suspension then I would say you defintely do need the right kind of rope and on that note to take a class or two. Bare in mind that if you DIY it and put pressure in the worng place for too long you can end up injured with serious nerve damage!
I recommend anyone intersted in real shibrai watch this video about safety and avoiding nerves:
www.youtube.com/watch?v=u9-VzX9_pzg
Also if you are in or can get to London the Anatomie Studio offers really friendly rope jams on Tuesday and Thursday evenings and full Shibrai classes at various times, they have plenty of proper beginners rope there for you to use but also sell proper beginners rope at £15 a length (to start you'll likley only need one length to practice things like single colunm tie at home) more info on their website here:
http://anatomiestudio.com/whats-on/
Finally I would also suggest anyone intersted in rope play get on Fetlife (make an account with a nickname and I would advise using a profile picture that doesn't identify you) which is a kinky social networking community type of site with plenty of groups and chats about all kinds of kink including groups dedicated to rope play and Shibari which you can join and find loads of helpful info on as well as ask questions on. Fetlife also has an events section which you can check out for your area and see if there's any rope classes or events near you. The website address is:
https://fetlife.com/
Fetlife is literally how I found my way into rope play and Shibari events and classes it really is the most amazing resource!
Anyway I hope that helps :)