Swee Lee sells plastic sticks, I think. They look pretty durable.
Also, if that's the reason you're going for aluminium sticks I would strongly advise against it. Opinion is divided here, but there are considerable reports of cymbal breakage when playing with Aheads, and Ahead sticks have been known to break when doing rimshots. Think of it this way - all that energy has to go somewhere, right? So far you've not had any drumhead breakage, that's because your sticks have given way instead of the drumheads. When you have a stronger pair of sticks something else is going to give way (i.e. drumheads and cymbals).
If splintering wood is your problem I'd look at Promark's oak sticks. I have the Stephen Perkins signature (719) and I can tell you, I have yet to hear about oak sticks splintering or experience it myself. Oak sticks will not splinter or break, they will only split down the middle from the stress when it reaches the end of its lifespan. However, as I mentioned earlier, all that energy has to go somewhere. With oak sticks it goes back into your hands. The vibration you feel when you play with oak sticks is maybe double what you feel with hickory sticks, so you have to have correct technique or else you may hurt your hands or tire much more easily than you did before. (Ahead sticks don't suffer this because they have an anti-vibration mechanism in the stick.)
If I were you, I'd look at oak sticks or take your own suggestion and try Swee Lee's plastic sticks. I'd stay away from sticks that cost $60+ and do not have complete assurance of durability. I suppose Ahead would be a good choice if stick wear is your problem, but your concern seems to be stick breakage. Try this little experiment: take a hickory stick, an oak stick, a plastic stick and an aluminium stick, grip each one by the ends, brace them against something and try to bend them. You will be able to get a feel for the overall tensile strength of each stick.
I think Swee Lee and Ranking also have metal sticks, but I'd avoid them because they're solid metal, unlike the Aheads. Wood can absorb vibrations well, and Aheads have a mechanism to compensate for that, but metal - you're going to get vibrations going both into your drumset and into your arms. Not very healthy. Or think of it this way: Wood vs Metal = wood loses. Plastic+Metal vs Solid Metal = 50-50 one of them gives way. Solid Metal vs Solid Metal is anyone's guess. I wouldn't take the chance on my cymbals.
