Price to repair intake manifold gasket on 2001 Buick Century

I have a slow leak and have an estimate to have the intake manifold gasket replaced. The cost to repair including antifreeze, labor (6 hrs)and parts is $550. Is this a fair price and is it a repair that needs to be done immediately. The light on the dash keeps saying "low coolant".

Asked by for the 2001 Buick Century
6 hrs is a fair time for this repair. It requires removing the upper manifold, lower manifold, and fuel rail. Draining and filling the cooling system, and I would recommend oil and filter change at this time too. These engines are known for this problem gaskets have been redesigned several times to help fix the problem. If you have a white milky look to your oil or antifreeze you have a internal leak that can damage your rod and main bearings, external leak only could be slow for a while, then cause heat related damage to your engine. It is a pretty important repair, however if you watch carefully could go a couple weeks to get your money together.
Thank you for your info. Appreciate your prompt response too.
I just did the job on a '98 Grand Prix. The plenum melted and coolant went everywhere that it shouldn't. This is what I paid.

$100 for gaskets
$220 for the intake manifold
$75 for the plenum
Plus labor, I got away with some bud light and $100 to a friend.
Also consider a case of oil, two filters, and coolant into the expense. (I changed my oil right away because it was milky then changed it again the next day.)

Took 6 hours with a certified mechanic.

To put the icing on the cake I had to buy a new starter ($160) and a Map sensor ($55)

Good luck.