We couldn't justify Hadoop until we were +6TB... that was some years ago, pre ssd and pre big disks - our old rdbs server had got horribly complicated because it hit that scale - when it got to 10TB its raid controller corrupted the control files for the db. We had support and the consultants who came did a bunch of mind blowing work to restore it.
But by then we had everything on Hadoop and we were only maintaining one legacy app on the old box - which we had told the users was dead and buried in any case (but kept to maintain friendships and so on).
Back to my main point - some people think that analytics starts with a question, I don't, I think it starts with the data and instruments to inspect and understand the data. I think that you should get the data on some sensible box, put a good database on there that your guys can use (as they are SQL folks get an SQL one) and put R, R-studio and R-shiny there and start inspecting and understanding it.
If no questions or insight arises then little is lost and it can go on a cheap fileserver until someone needs or understands it. If nuggets of gold start appearing then you can invest further in both skills and kit. I would recommend Hadoop either if other datasets of the 10gb+ scale start appearing or if this one gets >4TB. The other database recommendation would be because of mega joins - which Hadoop does well, and the general need to build a cheap EDW - if you have lots of cash you can build an expensive EDW instead! 4TB because currently disks are ~6TB and there are nasty scaling bumps in not Hadoop world that start kicking in as per my experience.
IT are right to charge once this is established to be valuable; if it's work £250k a year to your business then it makes sense to be spending £50k a year to put SLA's and resiliance on it. If it's worth £2k... well...
I assume you don't have someone/some system 24/7 pouring over the data so you could look into hosted notebooks like databricks, qubole (and gleaning from people I met at a recent conference any of the bazillion that are about to launch), or host zeppelin yourself or use AWS EMR.
And don't lose your source data for that moment when you do figure out what you want to do with the data and you realise you need to reformat it.