First, there are two 趟 in this sentence, so let's distinguish them.
The 趟 in 犁过多少趟 has basically the same meaning as the 遍 in 趟过多少遍.
And the 趟 in 趟过多少遍 is like a term with respect to farming, and it has the same meaning as the 犁 in 犁过多少趟. They both means to turn over the soil, remove weeds and cultivate soil for the seedlings.
When you are 趟地 or 犁地, you need to go back and force in the farmland.
Here in the context, it means that these 行家 go back and force in the market everyday, which implies that they are quite familiar with the market and have seen almost every item/antique in it. Maybe you can think of it as an analogy.