I think they're necessary for IWB or OWB carry. I can understand trying to avoid buying a lot of extra equipment while you figure out what works for you.
For casual wear, I like to use the Wilderness Tactical Instructor belts, 5 stitch. My first one has the original metal buckle, but next one I bought has the plastic buckle. For a dressier belt, most of the custom leather holster makers also make belts. My leather belt was made by Little Bear Leather, but they're out of business. The "Double Duty" belt from Cabela's is not too bad. All leather belts for holster carry are THICK, as they should be. I'm always surprised to see postings on the 'net where someone complains about their leather gun belt being "thick" or "stiff." I have 2 leather belts that were free from LA Police gear. They're ok, but not as good as the others already mentioned. Google custom leather belt makers. A good custom leather belt for holster carry will run you upwards of $50, but it will be money well spent. Depending on the maker, the wait may be weeks to months.