Depends on what you are asking the GC to do. For a renovation project this sounds a bit low to me unless it is a quick in and out type of project with little complexity. Mark-ups and charges are all over the board depending upon the type of company the contractor runs. Charges for a design/build firm would be higher than a contractor that is a jack of all trades and operates more as trade labor. If the firm has an office, design software, staff and employees for labor then the charges will be higher than someone who works out of their home and has no office space. A GC that builds new homes as well as completes renovations will generally be less expensive than a remodeling expert. There really are no standards.

Costs are always in a strong dependence of the location. And if you write the exact location of the condo, you can get contacts and offers of the right contractors also here on houzz.
And about managing the project by your self - this is always an option, but you need someone to be on the site and to supervise the process, in order to get the results you wish. So when you already have offers from GC, you can see whether it is cheaper to be there physicaly, taking some holiday or to hire a pro.
Also it is very important, especially if won't be there, to give very clear instructions to the contractor, including plans, visuals, materials/furniture specifications and similar, to ensure there won't be any misunderstanding.

We just finished a major interior remodel and our contractor got 20% overhead. Worth every single penny!