All depends on an audience on which your site is calculated. If your company has a certain share of the market in the given regions domain registration will allow you to interest in this zone большее количеÑвтво potential clients and partners in business.
RU-domains costs from 3 to 15 usd. Prices on the middle-costs domains are 300-500 usd. Registration in this zone is easy, but not by PayPal.
.ru will help you to get listed on Yandex and Ramble. So, if you with get to people in Russia (or Russians overseas), .ru is a good choice. GM