Nova Craft sp3 is tough but heavy,Fiberglass is 10 lbs. lighter and can be patched, Is Fiberglass worth the extra cost for the lighter weight and that it can be fixed easy.
Carbon,Kevlar and Graphite just not in the budget.
What boat model and what is your use
Nova Craft SP3 is simply a moniker for triple-layer, rotomolded polyethylene, similar to the Old Town Discovery canoes.
Three layer poly is tough, but very heavy and depending on the boat model, and cross sectional hull shape, many three layer poly boats will tend to deform somewhat as they age. This does not necessarily profoundly affect their use in most cases. Polyethylene boats, three layer and otherwise, can be repaired but are usually more difficult and more expensive to repair than composites.
Any polyethylene boat longer than 15 ft or so is going to be unacceptably heavy, in my view, if anything more than minimal portaging and occasional car topping is anticipated.
Not knowing…
what your usual use is, all I can say is that unless you are using the canoe in rivers with a lot of fast water and a lot of rock, glass is the better chioce. I own both glass and Royalex canoes, using both on Ozark streams, which are class 1 and more gravel and small rocks than boulders and whitewater. I never baby my canoes and I float a lot of skinny water, so the bottom gets beat up. My glass canoes are worn through the gel coat and exposing the glass weave on the ends, but still going strong. The glass solos are faster and better tracking than the Royalex ones, due to the sharper entry lines, while the Royalex solos I own are more maneuverable, so I use a glass solo on slow rivers with lots of long, dead pools, and a plastic one on faster, narrower streams.
Hope that helps.
material
How are you going to use the boat? Fiberglass can be formed into more useful and efficient shapes than royalex and sp3. It is lighter and plenty strong if you can stay away from rocks. I have used fiberglass and wood canoes plenty of times on river trips, but never in bony rivers full of rocks. Then Royalex and the other man-made materials are better.
A couple of thoughts
I have had several high quality fiberglass canoes and would say they take abrasion very well and are easy to repair. For rock dodging however I have used Royalex which can really take impacts above or below the waterline. It is lighter and stiffer than polyethylene and still common in the used canoe (Craigslist) Market.
In streams I am a big proponent of using air bags with any material. It is boat insurance. Swamped canoes float very low in the water without extra floatation and are much more likely to get bashed or pinned and crushed on underwater obstructions.