Will you be buying an Easter gift for yourself, or will it be from someone else, i.e. other half? If it is from someone else, why not ask for something non-food related. A nice bunch of spring flowers maybe?
If it is something you are treating yourself to, then there are low Syn options out there.
What about the mini Malteaster bunnies? You buy them in a pack of 5, and they're only 3 Syns each. So even if worst came to worst and you ended up eating the whole back (15 Syns) in one go, you'd still be within your daily limit.
Creme Eggs - standard size are 8.5 Syns each, or if you buy the bags of the minis they are 2.5 Syns each.
Cadbury caramel bunnies - these now come individually wrapped and are 5 Syns each.
Even a "proper" easter egg can be had on SW. As Tamkat said, you can weigh the egg and break it into maybe 5 Syn portions, bag it into sandwich bags and let yourself have a bit each day.
Hopefully this will give you a few ideas.