okay. i think i found the best value beans so far.
exportacion - from cafe risso. it's to the left of rustica in calle risso, lince, lima (beside the plazavea/casino/mcdonalds complex).
their exportacion vareity is/10 per 250g, and s/40 per kg, and tastes like the coffee you would normally get from stores outside peru. it is in fact the same beans for export, i think.
their "super premium" or i forgot how they call it (for around s/7.50 per 250g or s/30 per kg) is robusta, or blended robusta/arabica, i don't recommend it unless you specifically love robusta.
their caracolillo variety is at s/12 per 250g or ?s/45-48 per kg, it's good, a lot cleaner in taste but a lot less rich than the exportacion variety, and i prefer exportacion over this one.
i've bought 250g each, of the robusta and the caracolillo variety, and about 1kg of the exportacion so far. never tried buying a cup of coffee from the store. based on the previous comments, sounds like their machine is not calibrated/not clean.