I use an internet-based financial system called Xero (www.xero.com). It's very very good, particularly as it accepts feeds directly from your Scheme's Bank Accounts, so reconciliation is a breeze, and it's invoicing (for Levy Contributions) and reporting capabilities are absolutely first class once you have set everything up.
The only problem is that Xero's fees are based on the numbers of accounts receivable transactions that you have (Levy Notices in your case), so depending upon how many Lots there are in your Plan and how that number sits within Xero's charging bands, their fees may be attractive or otherwise.
We pay $49/month for a 27 Lot Plan.