The Covetor is 1/5 the price, at 20 million ISK, where as the Hulk is a solid 100 million.
But, if you need a mining ship that can tank most ratt BS spawns, especially in Null security space mining, the Hulk is your Mining ship.
The Hulk is in a Class of it's own, called Exhummers. All exhummers get a mining bonus per level trained. They also are able to fit 4 mid slots, compared to the Covetor's 1 mid slot. Exhummers also have increased Shield Resists, HP and capacitor.
I will let you in on my uber Hulk Shield Tank Fit. It is able to easily tank most ratt spawns, allowing you to either keep mining or allow additional time for friendlies to kill the spawns or let your Medium Drones finish them off, before your tank breaks.
My Hulk's Uber Shield Tank is as follows;
3x Modulated Stripper II's with T2 mining crystals
1x c-type pithi shield booster
1x Invulnerability Field II
1x Cap Recharger II
1x Magnetic Field Scatter II (passive EM shield resist mod)
1x MLU II
1x Power Diagnostic System II
The Mid slots and the PDS2 in the Low is what makes this shield tank able to be run Perma, while running the strippers. You will need to stagger your 3rd stripper, as to not overwhelm your capacitor recharge rate.
Since, the Hulk has naturally amplified Shield Resists, across the board, adding the Invul II and Magnetic Field Scatter II will give you amazingly high Shield Resists. 77/75/75/66
Do not forget to train Shield EM Compensation to 4 or 5, to make the EM Magnetic Field Scatter II Shield Resist module even better!
The only way you can make this tank stronger is to use a B or A-type pithi Shield Booster. However, the B-Type will cost you upwards of 60 million and the A-Type a whopping 450 million ISK for a single module! While the c-type goes for around 12 million ISK.
The C-Type Pithi is almost as regenerative as 2x Small Shield Booster II's, but consuming only a fraction of your Hulk's capacitor.