Selecta is a common trademark in Spain, widely used in spanish laboratories, with relatively good quality. Of course, it is not the best one, but getting -20ºC  does not need very god technology. Probably, with time, the limit of -25ºC will be difficult to get. This also depends on the capacity. Your choice.

good luck 

if you have a limited budget, buy a common consumer freezer - they are much cheaper and work fine - just be sure not to buy a "no-frost" type, which cycle up the temperature briefly to eliminate frosting. Freezers without no-frost feature, tend to be cheaper (and better for biological samples as they maintain a constant -20C).

In US freezers rated at slightly lower temp than -20C from scientific suppliers have a little extra storage capacity, have a temp indicator on the outside and an alarm - all these added features make these freezers cost about 3x more. The last two features can be added by you for a mere $50! Three freezers will give you far more storage and redundancy, should one fail.

Good luck!