Even if you don’t have fixtures I would definitely buy them for that price - otherwise you will kick yourself in future when they are all gone!
The PowerGroove tubes were invented by GE’s
Gene Lemmers and
John Aicher in 1956 as a clever way of solving the problem that the efficacy of fluorescent tubes rapidly drops when increasing power. It allowed an increase to 2.2 times the normal light output with only 2.5 times the power dissipation. The indented glass tube increases electron temperatures within the discharge, which leads to reduced electron density, and under such conditions lamp efficacy is increased. The first lamps had single-sided grooves but in 1960 a further improvement was made with this double-sided groove shape, which fits the arc of a 9-foot lamp into an 8-foot tube and further increases output. Mercury vapour pressure is kept low (to maximise efficacy) by two special slanted grooves which produce a cool spot near the tube centre, and two missing grooves at one end. As such, GE’s development introduced the first VHO tubes and the range was set to operate at 1500mA.
It was an exceptionally difficult and expensive lamp to produce, and only possible to keep costs under control because GE used to also make the glass itself. When Sylvania and Westinghouse tried to copy the design, they were unable to compete because at the time they bought glass from Corning who demanded ridiculous prices to mould the special bulbs.
Later they both also started to make their own glass, but until that happened Sylvania achieved similar performance as GE’s PowerGroove by a far more elegant solution.
John Waymouth’s brilliant mathematical modelling of the low pressure mercury discharge demonsrated that he could achieve VHO performance in a simple low-cost T12 bulb simply by changing the gas filling from argon to neon, and introducing a pressure control chamber behind one of the electrodes. Sylvania marketed its far cheaper VHO 1500mA series at the end of 1956, and this was subsequently copied by Westinghouse as its SHO tube. It was so much cheaper than the Powergroove that GE also ended up being forced to copy the Sylvania T12 Neon solution to survive in this business. Remarkably GE carried on offering both that and the expensive PowerGroove solution for many years, until eventually dropping the PowerGroove and only offering Sylvania-style VHO tubes. There is a nice article on these developments
here