The newer micro grain carbide inserts are likely much tougher than the old style carbide. High speed steel inserts are also available in cases where carbide brittleness may be an issue.
If you really want to save money on carbide inserts buy off eBay. Chances are you can find 10 packs for less than a single insert from the tuning tool manufacturer. The inexpensive eBay inserts will be counterfeits from China, but for wood turning you may not notice the difference. Find a chart listing insert dimensions, etc, so you can order by the industry standard naming convention.
Something else you can do if you're put off by the costs of inserts and insert holding tools, make your own tools. Buy the inexpensive inserts, grind a flat seat on a mild steel bar and silver solder the insert on. Surprisingly easy.