One thing that can happen quite often to a violin (that is often overlooked), is the ability for the sound post to move around inside the instrument (every instrument has a sound post that is mobile). This causes a big difference in how the instrument resonates (the post connects the top and back), and bumping it back into an optimal spot can be worth the $10-$15. I often find instruments sound “dead,” and a simple sound post adjustment will bring your sound quality up quite a few notches. I suggest asking him to take a look at the inside of your instrument and see if the post could be moved slightly to a better spot. Ultimately when you are ready as well, a better quality instrument will be the ultimate solution.