We've done a handful of Ignition Limited packages for around $5k (our cost) with a single client, but just about all else unlimited, often including alarm notification. I think the least expensive package we used also had a tag limit and was under $3k.
If it were me just getting started, I would look seriously at the Red Lion CR3000 series HMI which can do lots of data logging, FTP that data to a PC, supports a sweet browser based remote access, and can bridge most any protocols between devices.
Most equipment needs an HMI, and switching to the CR3000 would give you a hardware based HMI plus a lot of power to share that data without becoming dependent on a PC or PC operating system for data integrity since the HMI and the memory card will keep right on collecting information within a few seconds of being powered up and for up to 200 days before purging the oldest log files from the card.
