I always judge a question about this based on how long I will be using the weapon (or item). Of course, sometimes it isn't a guarenteed time or rep grind and it's a RNG thing - so you make the choice. If you will be playing with this weapon for a month or longer - then heck ya it's worth it. If you think you will be upgrading within a week - then why would you bother. But, then again some people are so rich and don't care they might very well blow 10k on this for 1 week and not think twice about it.