Should I buy WH1+DLC rather than buying WH3 DLC?

So the other day I was super excited to try some new factions like Tzeentch and Beastmen but after finding out they need DLC to complete their roster I am in the dilema of waiting to buy the DLC.

If I try to play these races now I feel like I am limiting my experience and don't like replaying the same campaing twice in case I buy it in the future. But on the other hand I don't wanna expend my money on some overpriced expansaion just because of a few units.

Would I be getting more ban for my buck by buying the complete WH1 instead? I already own the complete WH2.