H-m-m-m, first question is, are you only looking at new, or
will good condition used/demo/b-stock etc. work? If so, you have a whole lot more choices. Some more models in your range to check out: Vandersteens are more boxless than most, and the 2CE Signatures(Class B, Stereophile Budget component winner)will mate well with the Arcam. My own Vandy's(Model 1's)have been hooked up with success even to a lowly NAD, let alone 100 watts of Arcam fron end. The 2's have a more cohesive tonal balance, and will be more muscial AND forgiving than a lot of alternates. A pair of used Vandersteen 3's will generally fall in your range, and are well worth grabbing. The Arcam will just about fit the bill on these, although a tad more amperage would be even better. Hales will work OK with the Arcam as well, but try to find some used.
The Diva's mentioned above are a good bang for the buck, and reasonably efficient to boot.
The 1.6 Maggies are incredible, but like all Maggie's will take all the power you can give them. Kind of like Thiels, which I would probablynot mate with your Arcam.
There are some decent used deals on Acoustats and the slightly more troublesome Apogees out there. The hybrids may work well, although the full ribbons might be a tricky
match. Newform Acoustics is one of the easier loads if you are looking at ribbon magic. Highly recommended - you will notice they hardly ever come up on the used market, but they have good models around $ 2K.
Have fun!