You can use both options as both require investment from your pocket.
As an eCommerce store, both options are suitable for you. But as you are concerned with brand awareness, SMM is the best to prefer over SEM because you are new and your brand needs more visibility in the market.
Did you know? Almost 75% of internet users search social platforms to know about a brand. Hence, these platforms have become an arena for brands to attract more audience towards them.
SMM is time-consuming as people take time to recognize or remember your brand. For this, you have to maintain consistency in contact with your audience. You should run ads, publish, and share visual content on other social channels.
It is a continuous process, and you must stick to the routine. This process will lead you to build trust for your brand.
On the other hand, Google Ads run for a short span. Once you stop paying the advertisers, you stop getting traffic from the search engine. So at this moment in time, you should focus on how your brand must reach the last audience online.
Coming to your second question, I prefer choosing a social media agency that will be helpful for you.
There are some beneficial reasons why I suggest opting for the social media agency. Here it is:
1. As the user base is increasing on social media, you have to post frequently about your products on social platforms. Creating content and running daily can be an extra load while managing your business. So, taking help from an agency will lighten your workload.
2. They have tools and resources to track engagement and behavior and plan strategies accordingly. Skilled professionals on their side know how to implement them efficiently.
3. Your In-house team may run the campaigns, but you are unsure whether it will work or fail. If it works, it is good, but what if it fails? As a startup, you should not take a risk until you understand the market correctly.
Agencies are experts in it and will take care of your goals with utmost dedication and give their best to generate positive results for your brand.
Above all, whether you work with the in-house team or hire a social media marketing agency, you will be spending a few bucks for your business. So then, why not join hands with the experts and benefit from them with tricks and know-how to deal with the evolving market condition?
I hope this suggestion will work for you better.