Increasingly, clients have been requesting integration of their software with Sage (mostly Sage 50 Accounts, but occasionally CRM or Act! also). So we have joined the Sage Developers Programme which cost us £1,700 + VAT. You get a lot of stuff from Sage for your money (including lots of Sage software to help run your own business).
The down side is that so far the support from Sage is a bit lacking. You don't get a lot of tutorial information from Sage, you just have to work it out for yourself. I think that they will supply training for developers, but this is at additional cost... Compare this to the enormous amount of free tutorial information available from MS et al, and the £1,700 starts to look a little steep...
I have been toying with Sage 50 2009. It took about two hours to get a simple application compiling and running. The delay was mostly due to this error:
System.Runtime.InteropServices.COMException (0x80040154): Retrieving the COM class factory for component with CLSID {A29354FB-35FA-4CD4-8261-DAD864982348} failed due to the following error: 80040154.
at SageTest1.StockLevelCheck.CheckStockLevel() in F:\ResearchProjects\SageTest1\SageTest1\StockLevelCheck.cs:line 17
at SageTest1.SageTestForm.CheckStockButton_Click(Object sender, EventArgs e) in F:\ResearchProjects\SageTest1\SageTest1\SageTestForm.cs:line 26
This is pretty much the standard "COM class not registered" error. It took me an hour or so of uninstalling, reinstalling etc to realise that all I needed was a reboot! After a reboot everything worked fine. For the record, I am using Windows 7 Ultimate 64 bit.
My next task is to work out how to check the current stock level of a particular product... Wish me luck!