I am trying to figure out what year Remington took over production of Marlin lever actions, becuase from what I have read and heard, the quality of the rifles went down.  I am looking at buying a used 336 in ok condition w/ scope at a local store, but I want to avoid buying if it is post-Remington buy out.  On a side note they are asking $250 for the rifle, does that sound like a fair price?

Older Marlins have a JM barrel stamp and the newer Remington Marlins have a REP stamp I believe.
Also the serial number on the Remingtons start with MR.

Edit- not sure of exact time they took over but I would say late 2009,that's when I bought my 1895 45/70 because I heard the were selling out to Rem.

There were a few issues when Remington first took over because of the transition. People, moving equipment and so on. Happens everytime something like this happens. Looks like things are running great now, at least if my newer purchase of a 1894 C is any example. Smooth as any Marlin, more accurate than I would expect from a Marlin, furnature fit and finish are as good or better than any Marlin I own or ever have owned. YEP, it has the dreaded Remington barrel and if I went to buy another lever action today, I wouldn't hesitate one bit at buying a new one made by Remington. They have been building rifles with some of the best barrels in the business for many, many years. I personally beleive they will be just fine...

Remington didn't buy Marlin, The Freedom group, which is a Cerberus Company did.

$250 is dirt cheap.  As mentioned above you want one with the (JM) barrel stamp.

Besides the JM proof mark, look for a serial number that starts with numbers, the Remington made guns have serial numbers that start with MR.

Cerberus bought Marlin in 2008, but the factory move was not completed until 2010, so there's no "magical" cutoff date, but the QC problems started showing up shortly after the buyout.
As already posted, look for the JM barrel stamp. Remington guns have a REM stamp.
As a point of reference, Marlins made in 2007 have serial numbers starting with "93"; the 2008 guns start with "92", the 2009 guns with "91", 2010 guns start with "90", and 2011 guns with "89".
Marlin leverguns made since 1969 do not have a letter prefix serial number (except for the "BO"s in 1972), so, if "Remlin" is starting that, it will be a quick way to seperate the sheep from the goats from here on out.  

and from what I understand, George Soros owns Cerberus. True?

NO!

 

Correct! But neither is owned by leftist George Soros as some claim.  They are NRA approved companies.