turnips will lend the necessary flavor but can be added WITH:
Cauliflower or slightly cooked potatoes such as Petite Potatoes (grade C which you can find at a farmer's market but pack some taste...yum), Yukon Gold, New Potatoes, Red Potatoes or Fingerling Potatoes.
I know some people who have substituted rutabagas in recipes with the stronger portions of a green cabbage (do NOT use the core). I came from a poor community and you learn what you can use and not. Things that grow in your garden like: the aforementioned vegetables and brussels sprouts, cooked parsnips, carrots, corn, peas, radishes, zucchini, cooked butternut squash, toasted or grilled eggplant or cheaper items at the store like jicama, cabbage and celery. Don't forget that some raw slivered (not already roasted) almonds, sunflower seeds or cashews will give you some more crunch too. I know that this is an old post but some people will find this in a search for the same issues like I found in my Google search... so Good Luck to all :)