Andrean, I would sure get a quote or two. You can rent floor sanding equipment but is can be quite a job and very messy. With the DIY projects we are doing, it's a trade off between the time that we spend and the money for the job to be done by a pro. The enjoyment of the DIY part can get a little strained with some jobs.
When you talk to the pro, you can get an idea how much more removal he will expect and his suggestions on how to go about it. A little sanding with a big belt sander can reduce a lot of backbreaking work, but changing expensive sanding belts can get expensive also. He will be able to see the problem, judge it and guide you.