Intuit has Quicken Essentials for Lion which is also somewhat compatible with Mountain Lion. Intuit also has a Lion version of Quicken, whose existence now is only visible through archive.org for existing Quicken 2007 users, and I am told may still be obtained by contacting Intuit directly.
There are alternatives listed on Macworld may also work for you.
Note the issue with Quicken 2004 documents and earlier stated at the end of this file if you have 2004 or earlier.
Any spreadsheet, including
can handle csv exported data without assuming pre-existing balances on accounts. It appears that even with Quicken for Lion's release, those with Quicken 2004 or earlier files, have to take additional steps. Those steps were nicely summarized for me by MichaelLAX as the following:
1. While still in Snow Leopard, download Quicken 2006 PPC from Intuit:
2. Open your 2004 or older data file in Quicken 2006 PPC and it will convert the data file.
3. You may now open this converted data file in Quicken 2007 for Lion/Mt. Lion (which will also run in Snow Leopard).
I personally have not faced this issue, as I haven't used Quicken since the 1998 version, and am going based on information posted in the forum.
Also you can frequently run Snow Leopard Server under Lion or Mountain Lion, if you no longer have access to a machine with Snow Leopard, or import the file into a Windows version of Quicken and run Windows on your Mac. Mind you the latter solution I would only do if actual account # info is not present in the Quicken file, or you have made sure your Windows is secure from intruders.