roundabout for approximately

Dear All,

as a silent observer of this forum I finally decided to join and, hopefully, to contribute. I have been training English, Spanish, Italian for nine years now, working for a big German car producer and some of its suppliers. I often hear that my little sheep use the word "roundabout" in connection with figures to express "about"/approximately e.g. they say "this will cost roundabout 50.000".

I know that you might use "roundabout" in this context, but I do not like it very much and I personally would consider it colloq. English and an expression you should not use in business English. Now my question to the native speakers all over the world:

Would you use "roundabout" in this way? Would you consider it bad/good English? Would you use it in business (even in an informal situation)?

I'd appreciate any comments (to support my point of view )

Cheers in advance

I agree - if a contractor told me my new roof would cost round about $10,000, I would accept that the same way I would accept "I can give you a ballpark figure" or "somewhere in the neighborhood of ten, twelve thousand dollars." But in a written bid, I would expect "approximately $10,000, depending on condition of existing subroof and availability of replacement tile" or something like that.