I've worked with nearly 100 startups over the last 10 years to launch their brands/online platforms and a common mistake I see is an initial overinvestment in the design and aesthetics when they start out. They spend tens of thousands of dollars and hundreds of hours trying to figure out the perfect logo, font, icon, packaging etc just to get their brand/service/product out the door. You can use design to really differentiate your company from the market, but early on there are other things that I think should take priority before overcommitting that many precious resources to design. That is absolutely not an excuse to be lazy or have poor quality work; it is more a lesson of seeing your design as an evolving concept and definitely an area where "great is the enemy of good" starting out. Designs and even brands can and should mature over time – I’d focus on a good quality and scalable design to start while seeking to iterate and mature it over time as your business grows in the first months/year after launch.
I'd also say that while startups tend to overinvest aesthetically, they generally underinvest when it comes to organization and documentation around their brand. Things like style guides and other branding materials are critical so you can maintain cross-platform branding consistency (and as your brand/design evolves you can continue to maintain those standards internally and with third parties by just updating the materials.) they also tend to underinvest in the wireframing and planning/blueprinting stages of designing their technical platforms (spending time during that phase saves time and money come time to bring in the graphic artists.)
So, to the question of “how much” a startup should invest; that is a little subjective. If you are a retail or consumer product brand of some sort I’d say spending a little more time and money makes sense since you have to include product and packaging design as well as possible displays in stores etc. If you are a digital brand then you may be able to get away with a more streamlined approach. If you are focusing on designing your software (web/mobile) applications then go through the wireframing process first so you can be crystal clear with your design partner what it is you’re looking for from them. It could be as little as a few hundred dollars or as much as $5-$10k starting out; it really just depends on what sort of startup you’re working on.
Feel free to reach out if you’d like to discuss your specific needs and talk further about your exact design needs and cost expectations.
The main question to ask here is "Why do people use my product or service?" If the answer is functionality, cost, or a variety of other reasons, then starting with a simple design and getting your product out there quickly is the best path.
If your answer is "All the other sites are boring, old-fashioned and uninviting" or you are simply coming in as a luxury brand in a space, then investing heavily in design is key. However, there are cost-effective ways to do this as well, such as creating digital mockups and gaining feedback from potential customers and investors prior to the full design work.
Let's chat further as I work with some very skilled designers at every level of your budget.