I'm looking to modify themes from themeforest, etc. to build sites for clients so I can market at attractive price levels. I'm wondering if people typically tell their clients that they are modifying themes when they do so and, if so, how that is generally received.
I think it is a technicality most clients do not care about. To me it is similar to saying that we are going to buy dodge vans to deliver your products. So long as it is well designed and they approve of it, most clients could care less what is used to solve the business need, their branding and results matter far more to their business case than whether or not a specific theme was used. For a pure web site that does not have much functionality, one would need a very good business case for not going with a theme. My group does custom web apps, and we have a division that does SEO analytic etc. The do offer packages for clients that need sites, and for almost every case a theme fits the bill. If a clients needs are publishing content such as marketing material, then it is almost a disservice to them to not offer a theme and pass along some of that savings to them, in the form of less hours spend on developing the solution.