So after almost a year of playing in alpha clone i picked up mining again, then i noticed that the venture ore/min is allot lower, which is fair. But there should also be a alpha accesible mining barge, although it should be very overpriced compared to the ore/min. And low ore space, thinking of a ship like 400/500 mil isk, depending on the fit. and 15.000m3 ore space, with 6 mining laser slots (same ones that fit on ventures for alphas).
What you’re asking for doesn’t make any sense. Or rather, what you’re asking for already exists: battleships. A bit over your budget, but with mining upgrades and up to 8 mining laser slots (plus mining drones), you can get what you want without a dedicated ship, although you do have to jetcan mine (which isn’t all that bad if you have a dedicated hauler in close proximity to scoop up ore from the cans).
CCP made a deliberate decision to make high volume mining difficult for Alphas. You can either play for free and be severely limited in your mining abilities, or you can pay to play and mine as much as you want with all of the platforms in the game.
Accept that and adapt, because anything else almost certainly runs counter to CCP’s financial interest.