The title says it all, so anyone?

Registration is never very expensive - $9 or $10 per year. I think they all cost about the same. (Unless .jp is more expensive?)
It's hosting that will cost you money.

SWI Forum, country code TLDs can be much more expensive in comparisation with most used gTLDs. Most registrars have price for .jp in 100 - 200$ range. There are few exceptions:
http://www.jp-domains.com/services/pricing.php - 69$ / year
http://www.marcaria.com/Japan/Domains/Japan-domain-name-registration.htm - 65$ / year
http://www.101domain.com/jp.htm - 79$ / year
I doubt that you will get it cheaper than that.

.jp is considerably more expensive than other common domain names such as .com,.org or .net
There are registrars that offer .jp registration but be sure that they are Icann accreddited,this is most Important.

Thanks testnick (http://www.webhostingtalk.com/member.php?u=81643) that's cheaper than anywhere I looked into .., .jp domains are expensive because they are restricted to Japan residents so the registrants would charge you for the registration and for using their Japanese address!

I saw .jp on GoDaddy for $99. Then on some smaller registars I haven't heard of like jp-domains.com for $69.
All the best,

idotz.net has .jp names for $89.95/year