How to model that several variants of a merchandise item may affect its price?
If the variants are identified by a variant code at the base of their sku, is the variant code always in the same place?  If so, you can always group together with the base sku.  

However, you might want to look at product grouping.  As an example, if your catalog of products is exercise products.  And you have fitbits.  The Fitbit flex can be sold with different colored bands.  Each one would have a sku of 1234 with a letter variant.  So bl for black, bu for blue, pk for pink.  so 1234bl is black fitbit flex.  

Now you can set up categories.  So the next level would be the type of fit bit.  You also carry the fitibit Charge.  That sku is 2345.  So one item can have a sku of 1234bl, a subcategory of Fitbit, a category of pedometer, under the store area of technology.  And you can group the data at those various levels.  A vp of Electornics might only care about the Category and the technology level.  Yet a Category manager cares about the sub category and category.  They may also care at the sku level.  

Does this answer what you are looking for?