That depends on how much and how old the equipment is. I always think it's a good idea to buy some used equipment. I did buy my diagnostic set and BIO brand new with a student discount and will have those covered under warranty while I'm in school. This type of equipment changes every handful of years so I wanted the more updated stuff. I wish I bought my trial lens set used. I did end up buying a used Digital Wide Field (90D), and 20D along with some of my entrance exam materials. I'd recommend finding used alternatives for the equipment that does not ever change (randot, ishihara's, random test targets, etc.). Look for used stuff (less than 5 years old) off of eBay or from someone in the graduating class to maximize your money (that is, if the equipment you stand to buy is not in good condition).
You should definitely consider your comfort level with debt. While yes, the new equipment will be cheapest when you are in school, remember that many people still do end up selling their equipment because the practice they will be joining already has the stuff needed.
The bottom line is, regardless of your decision, always be aware of how much you're paying for your equipment and how much it could cost elsewhere. Try to keep all your receipts for equipment and books because you may want to use those as a tax write-off in your first year of practice after school (not sure of all the details, but I know its possible on some level). The more you save now, the less you have to pay back in the future, and when it's all said and done, you'll get through optometry school just the same whether you have a used corded $600 BIO or the latest headmounted battery wireless BIO for $2200 (a splurge I went for because c'mon, wired electronic devices are so 1998).
