Best & Cheapest way to move a few boxes cross country?

I'm moving a few boxes and golf clubs across the US in August that won't fit in my car. I have 2-3 45L boxes and golf clubs that I'd like to move. I prefer to ship them together but I'm not sure if there are any options available for such a small move.

My car is a small luxury sedan (A4, BMW 3 series, is250, q50)

Thanks!