You seem to be suffering from cronic bad luck! I suffer from the afliction myself.
There is no cure for it only some ways to minimise the impact as for as sporting goods goes (1) only buy the cheaper stuff when it doesn't realy matter,(2) hold off till you can buy what you realy want the first time when it does matter (BUY ONCE CRY ONCE) (3) Talk to people who own the item you are interested in and not just any body, people who you consider to be more knowledgable than your self , If I asked my co workers , neighbors , ect. what would be a realy good scope, I would here "tasco, BSA, redfield, simmons ect.". Not that they are bad, they just are not long range precision hardware.
I bit the bullet and purchased a NF nxs 3.5-15 50mm 6 months ago and it took a little while to rat hole that much cash but 6months later it is the best money spent in my shooting sports history. A year ago I purchaced a $350 optilogic range finder that was supposed to be good for 1500 yds , after a blown oppertunity this past fall where I could not get a consistant reading at what turned out to be 712 yds when it was ranged from the elks location back to a big rock I was shooting from. I knew then that I was once again a victim of my cutting corners in a arena where you get what you pay for. That was 5 months ago and 2 days ago I ordered a G7 br2
rangefinder and yes I cried but I will only have to do it once!