Bounce and diffusion has already been covered with the OP. Reality is that light quantity and quality (color temp.) varies throughout the day, so a longish daylight scene needs supplemental lighting.Well through a series of mirrors you can get real sunlight if the budget is that small.
Totally forgot about them!
Going LED is a better option perhaps. Wifie prep's LED Leko's often and there is lots of concepts of Fresnel and PAR or other ger out there. Ushio has some very interesting LED gear. Main question in a wide ranging subject of PAR beam to audience blinder/9-lite, what's the goal of getting this beam or wash of light?
Let's break this down:Ship the goal, is getting a clean, stark daylight look through a window that an HMI provides, but on a shoestring budget. Hence the initial search for the (mythical) daylight PAR64 globe and the need to have less than the 50% transmission loss through the use of color correction filters on Tungsten.
CTB, not CTO. CTO would give them a lower color temp.Renting a Mover for a daylight look through a window is like renting a Car so you have access to a radio.
In my humble opinion, Just use CTO or a gel in front of a normal PAR. THAT is the cheap and fast solution that the OP is looking for. Anything else adds complexity and cost which the OP says they don't want. HID PARs are long discontinued. Another option is to rent a small K5600 (or Mole, or ARRI, etc.) ~400W-800W HMI fixture and a DMX controlled Louver. That will give them the Color and output they are seeking, without the added mover complexity of ~19 channels of DMX they won't use.
Let's break this down:
1) "stark daylight look through a window that an HMI provides"
2) "shoestring budget"
To me, the answer would be to rent a mover that uses a discharge lamp for the show. That will give you the beam effect with the right native color temperature, and the ability to mechanically fade in/out in one mountable package.